Spoony's Strategy Guides: Field
In the last year or so I have been extensively playing clan games i.e. small games compared to public servers, and unlike public servers everyone is working in co-ordination. So I now present a strategy guide for small games, starting with Field.
These strategy guides all assume the starting credits are zero.
 My general Renegade principle
Before I actually begin the Field guide, I'm going to explain a principle by which I generally play. It's extremely simple, extremely effective, and it frankly baffles me that the vast majority of players in public servers don't seem to understand it.
The principle is this. If your enemy has powerful and expensive weapons, destroy them before you attack his base. I'm being theoretical here, but here's a demonstration of what I mean. Let's say the map's Under and you're on Nod. Let's say there are a couple of GDI players who are camping in front of their AGT to defend the base. If you rush in with stanks, flamers or APCs intent on base destruction, you'll fail. The meds will smash up your rush and you won't kill a building. All you'll do is run out of money, while at the same time giving your enemy some nice fat points. Instead, get an artillery and some light tanks, and kill the med tanks first. Hit the weapon factory a couple of times with the artillery. This will force the med tanks to rush you, otherwise you would just get massive points... and when they rush, concentrate all your light tank/artillery fire on the med tanks. Then once the med tanks are destroyed, you'll have an artillery hitting the factory, a couple of light tanks ready to rush the AGT, and GDI can't do jack shit about it. Most likely, you'll kill one if not both buildings in that scenario. At the very least, you will build up a large points lead and get lots of cash for your next attack.
Anyway, bear that principle in mind as you read on...
To begin, GDI needs to get money quickly. There are three ways to do this: attack the Nod harvester, grenade the refinery, or grenade the airstrip. Generally the best option is to kill the enemy harvester, since it'll cut their cash flow for a while as well as increasing yours. Also, Nod only gets negligible money for fixing their harvester compared to fixing the refinery or airstrip when there are grenadiers attacking it. The most efficient job is one grenadier backed up by a soldier or two. Of course, be aware that Nod may try to ref hop you, or attack your harvester.
Assuming your harvester made it back safely the first time, you'll probably have around 500 credits or more if you've done a lot of grenading. One person should buy an MRLS at this point... and take it here.
This is a brilliant spot to deploy your MRLS, since you can hit any Nod vehicle which leaves base (including killing the harvester every time it comes out, which is a HUGE help), especially the Artillery (which is Nod's most dangerous weapon on Field)... a good MRLS player can easily wreck an arty before he does any damage. You're also relatively safe from return fire from a Nod Artillery since the hill will protect you somewhat, and anything else has to come close to hit you.
Meanwhile, your GDI teammates should continue to grenade the refinery and airstrip. By doing this they will soon have enough money for med tanks. If you have done a good amount of grenading, you should have your meds at roughly the same time as Nod can afford light tanks. Get your meds out onto the field as soon as possible, because you don't want to leave your MRLS on his own to get rushed by light tanks. You might think it's a good idea for someone to mine up at the start, but it really isn't. You need meds, and lots of them. An extra med tank is better than mining your base. Aside from anything else, if you have enough firepower in the field, Nod won't be able to rush your AGT anyway. You can always mine up later.
Good spots for med tanks are here
The spot by the bunker is affectionately known by clan players as "the med hill". It's really quite a nice spot to use a med tank, because you can easily hit any Nod tank coming out of their base, but it's difficult for Nod to hit you back. By the waterfall is also a great spot. While you don't actually have a hill to cower behind like the first two screenshots, you can retreat to near the waterfall when you're damaged. If an artillery/light tank wants to hit you, he has to come all the way out of his base... where he's vulnerable to attack from MRLS and med tanks in the spots I've already mentioned.
Anyway, regarding the principle I mentioned earlier. If you just moved up to the edge of Nod base right at the start and hit the Hand of Nod for points, you're asking for trouble because it's surprisingly easy for a teched arty (i.e. an artillery who is constantly healed by a technician) and a few light tanks to clear the area of GDI vehicles. However, if you hang back in the field, using the hills as I've shown, force Nod to come to you and also kill the Nod harvester every time it comes out, you've basically got the game in the bag. And once you've killed a few arties and lights, they won't have any money (due to the fact their harvester never makes it back). When this is the case, you can move up with your meds and MRLS, and hit the Hand. Rushing the obelisk is also an option.
Playing by this method, you only really need to watch out for harv walking (When your harvester goes back every couple of minutes, spare a quick glance to check there isn't a technician there... You can also block your harvester later on if you're OK for money) and nukes at the barracks/refinery. If you hear a nuke being deployed, one person should go back while the others hold the field. But be wary, because sometimes if Nod's having a tough time taking the field back from you, they might lay a fake nuke just so one or more GDI players will go back to check on the base, which will make it a lot easier for them to take the field, which is 1000 credits well spent.
Let's assume you try to take the field as above, but you fail and lose your vehicles. Nod will take the field with an artillery and some lights and start hitting your WF. In this situation, your course of action should be to fix the WF (and take potshots at the light tanks with a tank, if you can afford one) until everyone on your team has a med, possibly with one MRLS. Now, if you rush out in a rabble, you'll get owned. You need to rush out with all the meds at the same time, and most importantly of all, call your target. (This is where teamspeak comes in so handy). If all your meds concentrate on an individual light tank/artillery at a time, you'll probably take the upper hand. Whenever a med tank drops, the driver can heal his teammates, and possibly try to remote an enemy vehicle too, which will help no end. This is your best chance of taking the field back. A lot of people in public servers think you should let your weapon factory die every time there's an artillery hitting it. While that might work in a public server full of idiots where nobody works in co-ordination, it will never work at a high level of play, I guarantee it.
As the game begins, you basically have two options. Either you can concentrate on killing their harvester with engineers, or you can stop GDI from grenading your base / harvester. (While it may be possible to do both, it's a lot easier said than done... so pick one of the two goals and focus on doing it) If you take the second option, just get some Nod soldiers / shotgunners / engineers in the tunnel and have someone watching the harvester too. If you can stop GDI from getting any grenadier money, you have a big advantage because Nod's best tanks cost less than GDI's.
If your harvester survives (and GDI will be trying to prevent that), you'll have somewhere between 500-600 credits each when it dumps. One player should buy an arty while the rest get light tanks. (In larger games, say six or seven players on your team or more, get two arties). If you've played the opening game well, you'll have your tanks on the field before GDI have their meds, though they will quite likely have an MRLS waiting for you. If that's the case, keep your artillery safe for the moment, rush the MRLS with light tanks and kill it quickly so the arty can move out. Like GDI, Nod can also make great use of the terrain on Field. Light tanks here...
are a good idea, while your artillery should stay at the back hill for now, like so...
Nod vehicles using the hills in this position are extremely hard to hit with a rushing medium tank, since all he'll see is the tip of your turret. Add to that the fact you can move back and forth, and he'll have a really tough time hitting you until they get close, by which time your team will have chewed half their armour away.
Again, it might be tempting to move all the way up straight away and pointwhore off the WF, but it's really a bad idea. If you move right up to GDI base, they'll easily own your tanks with their meds. Instead, chill out behind the hills for now, kill the GDI harvester every time it comes out, and wait for GDI to rush you with med tanks. Just as it is true for GDI, it is vitally important for everyone on Nod to focus on the same target. This is where the artillery's range and power, and the light tank's low profile come into play. When a light tank is behind the hill as shown above, it can easily hit an oncoming med tank, and use the hill to shield itself from the med tank's return fire. This means a med tank has to get close to do some effective damage. And the artillery is out of med tank range anyway. By concentrating your firepower on one GDI tank at a time, hopefully you will hold the field. Probably losing a few lights in the process.
Once you've killed all of GDI's tanks, they'll be broke (this is why it's important to kill the harvester every time it comes out). Once they can't afford anything decent, you can move up, like so...
The artillery can pound the WF, the lights can rush the AGT if they feel like it, or just hit the WF as well and hold the field. If the lights rush while GDI has nothing to defend with, then chances are either the AGT or the factory will die. It's plain sailing once that happens.
Anyway, for the sake of argument let's say you lose the field, and GDI takes over with meds and maybe an MRLS. You need a teched arty here, and a couple of lights. One artillery should stay in the Nod base entrance with a technician giving him constant repairs. This will either destroy GDI tanks or make them fall back into the field, and once they do that, other Nod players can rush out with light tanks.
 Other strategies
Don't bother using stanks, it really is a bad idea. While you might sneak past GDI one game out of ten, the other nine times it'll do your team more harm than good because light tanks and artillery do a much better job, and are cheaper. Nuking the barracks or refinery is a possibility, but don't use that as the focal point of your gameplan, instead just pull it out of your sleeve every now and again to surprise your opponents. Like I mentioned earlier, if you're having trouble taking the field back from GDI, consider laying a fake nuke. Hopefully this will cause one or more GDI players to go back and check on the barracks/refinery. With less GDI firepower on the field, you'll take the field back a lot easier.