In reply to Kemics:
I find it tricky.
I generally do some light core exercises like side bends and hip circles. I also do reaches with my arms, simulating the range of movement I'd go through with a pull up.
Generally then I'll do some bodyweight squats, just 20 or so, then 2 or 3 sets of press ups.
Then I'll do 2 sets of 5 pull ups on the bar that I hang the fingerboard from. Then 2 sets of 5 pull ups on the biggest jug holds that the fingerboard has. Then 2 sets of 5 pull ups on the deep pockets.
After that I feel quite warmed up and ready to do hangs.