STEALTH TROOPERS- There are many strategies for these little pains in the asses, and most of them are described above. Another good tactic with these is on a map with no defenses, get three stealth troopers and run up to a building's MCT before the enemy has the time or credits to plant proximity mines. Deposit your C4 and defend it if any engineer comes in to ruin your parade. Also good would be if you happen to be lucky enough to find a spawned sniper rifle. They're pretty hard to find as stealth snipers.

HIDING SPOTS- If you're planting a beacon or rushing a MCT and you've managed to make it into the enemy base, there are a few good places to hide. Definately a good one would be a destroyed building. They are seldomly entered unless someone respawns. They're also good for cover.

ATTACK TIMES- A great time to attack with stealth would be while the enemy is attacking your base. They don't really have much on defense, and it's a great time to strike.

TUNNEL ENTRANCES- Whenever you're going to enter a base with defenses through the tunnels, try to seek cover by crouching near rocks. You can then run to the next rock and try again. If you're lucky, you can make it to the desired building, although it has to be pretty close to you. Another good thing to do is to just repeat this tactic and keep putting timed C4 on the wall of a close building as a cheap character. It won't do much but give you points, be that's a good thing, right? The obelisk is easy to dodge if you're infantry also, because you can just jump like crazy to avoid its beam.

I have a few more, but maybe I'll post them later.