I'm lucky enough to test fly a lot of my clubmates models for them, from trainers to large scale and 3d.
I always.

1. check the c of g.
2. check the control throws
3. check the thrust lines.
4. range check it.
5. ALWAYS make sure the engine idles and picks up properly.

Very rare for there to be a problem if you eliminate most of them before you take off.