Advanced Mining Techniques
This article expands on Ma1kel's mining tutorial, covering several more advanced topics that affect mining.
 The Ramps on Flying Maps
The buildings on Flying maps (City Flying, Walls Flying, and probably Glacier Flying as well) require special treatment in some cases due to the ramps leading up to the roofs of the buildings. Most players in public Renegade servers do not think of roof-beaconing buildings, however, most skilled players are able and willing to roof-nuke/roof-ion, so in, say, a CW (Clan War for those of you who don't already know), you should lay 1-2 mines on any ramp that is not covered by base defenses. However, remember the point that Ma1kel made about staying within the minelimit...
 Minelimit Headroom
It is not a good idea to lay all 30 mines in your base. Why? Engineer-type (APC, ...) rushes require a few mines free so they can use their Remote C4 blocks without fear of de-mining their own base. Leaving 2 mines free for offensive usage is the barest minimum, however, I recommend leaving more (up to 5) available if possible.
 The Tunnel Beacon that Isn't
The near-tunnel beacon spots that can be found in Field and Under pose a special problem for mining, especially if you are on Nod in these maps. However, simply mining the mouth of the tunnel is rather ineffective because then the mines are rather easy to disarm without being noticed. What I do is lay mines on and around key boulders and on the outside of the tunnel portal itself, which makes them much more inaccessible to maruding Engineers. Always go back and simulate a rush to said boulders to check if you can see your own mines - often the very fact that they cannot be seen is the best defence.
 Islands and Canyon
Islands and Canyon pose two other unique mining problems because of the balance between the tunnels and the field on Islands and the ramp structure behind the GDI Barracks on Canyon. The recommended approach on Islands is to treat the mouths of the tunnels in your base (and ONLY in your base) as building entrances for the purposes of mining the base. If you are on GDI in Canyon, you may want to lay 2-3 mines on the ramp behind the barracks as a deterrent to those who would roof-nuke your Barracks otherwise.
 The Pedestal
If you have lost your Barracks or Hand (shudders!) but still have a Technician or Hotwire, you probably want to keep the Barracks or Hand mined because if there are no mines in that structure, you are inviting the other team to come and lay a beacon on the pedestal. However, this ONLY applies to the Barracks or Hand and not to any other buildings. And, of course, when pedestal beaconing is turned on.
 Mining to Stop Vehicle Rushes
On Hourglass, Under, and Field it is effective to mine the entrance of the base to stop vehicle rushes. 5 or 6 well placed mines are equal to an ob hit and leave an APC well short of it's destination. This is especially effective when multiple APCs rush. The occupants of the first APC scatter as it is destroyed and the following APC has to slow and dodge its teamates. Don't mine the whole entrance, only the most direct route. Let vehicles take a long tac around the mines, they will take plenty of damage from the base defenses.
Sometimes, you might lay a mine or two at the wrong entrance or on a fellow teammate. This is OK as long as it is accidental. Don't attempt to lay more mines. It is imperative that you keep an accurate count of the mines you have laid and coordinate through game team chat (F3) with your team mates prior to laying mines.
 Multiple Miners
Unless EVERYONE mining ABSOLUTELY knows what they and their fellow miners are doing, avoid this at ALL costs. It usually leads to the minelimit being exceeded = disappearing mines = BAD.
 Offensive Mining
Granted, for the most part you should keep mines for a defensive purpose; however, there is that little extra you can get out of mines if used in a way for attacking!
First and foremost, you can mine an enemy building just like your own (in the 5 star pattern to guarantee kill an infantry). This is very useful when you happen to sneak your way into a building and there's only one entrance. Think of this tactic as "mining yourself in". Once you've placed remote/timed c4s on their MCT... the mines at their entrance will act as a great deterrent for would-be rescuers to the building, and if anything, will cause a large enough delay for you to destroy the building. If you have any extra mines, or you didn't use the mines in their entrance, you can also place a mine or two on their MCT. You might be thinking, wtf? Frequently, a n00b or two will run near enough the MCT to explode the mine and cause additional damage to the building, while possibly killing themselves in the process. Every little bit helps in those precious few moments when trying to kill buildings. Another fun place to put your mines is 2-3 at head level on the PTs to kill enemies right when they spawn.
Mining the MCT is probably one of the better strategies on buildings with multiple entries (particularly the Hand of Nod, which potentially has 4 different entry points. It disorients the enemy hitbox while they try to disarm your Timed C4, and helps you kill them off/forces them to spend time refilling while they're chasing you around the building. Naturally, it's better to mine the door in buildings like the Obelisk, AGT or Airstrip, but when there are 2 doors, your mines become useless because if you split them, the enemy will just rush straight in, and if you put them all on one door, the enemy will just take the other door.
Speaking of using mines offensively, as a Hotwire or Technician, you can always throw a mine or two at incoming enemy infantry to help kill them in a firefight... there are some drawbacks though. One, the minelimit of course. Two, you need to be pretty close to use them effectively (or be in a tight spot that limits the enemy's movement). Finally, being close to your own exploding mine will often times hurt or kill you when attempting to use them this way.
One of the semi-n00bish things you can also do, and be somewhat considered offensive mining would be placing a couple mines on the front of your vehicles for that extra punch to ramming enemies. Note that this is banned in many servers under the title "Flaming APC", even if it's only a few mines and/or the vehicle isn't an APC.
Offensive mining can also be synonymous with n00bish mining in that if you don't mine correctly/respectfully to your team... your mining could be considered offensive to your own team, especially if your server has a low mine limit. Nobody likes n00b miners.
See you in-game!