One of the few things that makes that easier are the Empire Defense missions, they give you 1000+ XP the first time you do them, and over 500 each successive time, plus 75 Badges of Exploration.
What I don't get is, if we get over a thousand XP for killing, say, twelve groups of Borg, why is that we have to kill forty-eight groups (three sets of 16 groups) for the 500+ XP and the 75 Badges of Exploration?
That seems backwards logically, not to mention plain out unfair.
Why not switch it? 500+ Xp for the first puny time, and the 1000+ for the larger groups required each successive time?
I believe it's the same for the "exploration" missions, where you will get diminishing returns on skill points. But I believe there's a similar effect on the Federation side.
If you want to level a character, definitely go the way of running the old Featured Episodes. I'm fairly certain they don't have the whole diminishing returns on those.
Actually, the exploration wrapper missions on the KDF side reward LESS points than on the Federation side. Even though some exploration missions are more involved for no apparent reason (having to kill 8 enemy squads instead of 6 for example).