Originally posted by OctoberSky:

Many thanks @Gisbert for the wiki reference. The progression formula was a question I've had for some time but that explains the quasi-linear XP gains.

You are welcome.

Rested effect is also an interesting thing. 50%... FIFTY!
Doesn't matter what task you do. Even if just a greydwarve comes by, kill it rested.
Just ALWAYS be rested.

Not be rested all the time is the biggest beginner mistake. Your character will get a hard diminishing return in the future, but by the time you write here and ask, it will be too late. Sure you can still balance it, but your only option then is repetitive extra leveling.