My players roll hp once, in front of me, and if they get a bad result they have to learn to roleplay. 
Harsh? maybe. But I always make sure there is a way out of every combat for them if they want to take it, and I award xp's for good roleplay, and avoiding conflict.
If you take max HP at first level (which I think everyone does) that already skews the average in your favour for your starting levels.

Harsh? maybe. But I always make sure there is a way out of every combat for them if they want to take it, and I award xp's for good roleplay, and avoiding conflict.
If you take max HP at first level (which I think everyone does) that already skews the average in your favour for your starting levels.