Given the 1.91.2 patch, I won't write about how to deal with degradation, but the rest is still fine.
1) You are the main target of enemy bots. Use this fact well! The rest of your bots can often go without a single scratch, as long as you're properly drawing away fire by yourself.
2) Keep a variety of droids with different roles in your "team" at all times. Try to avoid capturing several copies of the same model (unless that model is particularly cool).
3) DON'T waste all of your transfer points to get lots of low-level droids. Even in hard times, it's almost always better to save some points and then capture something high-level. High-level droids have much better stats and stay alive much longer.
4) Keep someone with a REALLY BIG GUN in your team to destroy armored targets (turrets, bosses).
5) Capturing turrets is generally not recommended on lower levels (until at least level 30+), it's a waste of points. Either kill them if you can, or run through. On higher levels, some turrets may be captured to help you kill hordes of enemies.
6) Try to AVOID picking upgrade powerups in combat (that is -- everything that's not Freeze and Rampage). Powerups do not vanish, you can pick them when all the opposition is dead -- also you can pick them more intelligently, applying them to different droids in your collection.
7) Switch between your droids often. Your personal droid gets the attention, so you can switch to save a droid if it's in a bad shape. Also switch before picking repair powerups (and especially the red one).
8) Use boxes intelligently! Boxes may (and will) contain more enemy droids, sometimes powerful ones, presenting a nice opportunity to capture them. But boxes only yield "treasure" if the level is not yet cleared, so it's pointless to smash them after you killed the opposition.