Some things I like to do as an eng:
-Pretend to be a spec ops. What I mean by this is, sneak around to their base. Don't steal the tank, but better yet, carefully plant 2 AT mines directly touching the front rollers of the tank. Usually the person just jumps in and takes off, happy that they actually got a tank to themselves, and blam. rinse and repeat.
-Use shrubbery and dark colored dirt to your advantage. Don't place a mine on yellow sand and expect it to not be seen. Water is a great place too, ahem songhua. Dragon valley has that nice little brook to put mines in b/c that's usually the first place the enemy invades in an apc or tank thinking they are safe. dead wrong.
-Think like a commander. Assuming the other team is pistol whipping, your side they must be following direct commanding orders and playing well in squads. Anticipate where the commander is going to attack next by taking a quick overlook at the maps and choke points. Which flag cap would make that team feel very comfortable? Stay close to it and monitor from a distance so you can hide the mines and watch the show. This will help in eliminating those AT mine tk's.
-Use the shotty as though you're trying to get your knife badge. Sneak around everywhere you go. Little to no armor makes this almost imperative unless you want alot of deaths every round. Listen to your commander and carefully picture the map in your head where the person is on the radar so you can come up from behind. It makes that one shot from the bad little shotty that much easier. Quick and easy. Nobody said this wasn't a dirty job.
-When in the m12a gun on armor and it needs repair, hop out and crawl directly underneath it to repair. It makes you much less likely to get sniped out or even noticed in the process. The other team will think that they are wearing down the armor when it's still at full strength. Only requirement is to have good communication and trust with the tank driver. It's quick to jump back in and duck inside.
I'll post up some more stuff if I think of it. I'm sure there is. Take this stuff for what it's worth.
-Alex