I'm pretty sure this is an already-known thing, but I just found a very cheap, easy way to get a lot of experience.
Every time you pay out a faction salary, you get 10 XP (no matter the amount of the salary). Basically, you can sit there and pay out 1 credit each time to yourself, gaining 10 XP each time. Find anything wrong with that?
Yes this is well-known and we have measures in place to monitor exactly this sort of abuse, so this is extremely easy to punish. If you choose to risk it, expect to lose the XP gained, an additional sum of XP as a penalty, and a ban in addition; that has been the standard punishment previously.