1st. you can rule that 10ft fall gives 20% max HP damage, 20ft fall 40% etc...
immersion in lava would be 30-40% max HP per round.
2nd you can make skills more expensive to level up:
i.e. 1st 4 ranks are 1 for 1, 5th to 8th rank is 1,5 for 1 rank and from 9th on all ranks cost 2 skill points. That would encourage wide specced characters as you would only have 1 or 2 skills maxed, maybe 3 as rogue.
immersion in lava would be 30-40% max HP per round.
2nd you can make skills more expensive to level up:
i.e. 1st 4 ranks are 1 for 1, 5th to 8th rank is 1,5 for 1 rank and from 9th on all ranks cost 2 skill points. That would encourage wide specced characters as you would only have 1 or 2 skills maxed, maybe 3 as rogue.