Better kits are more likely to fail completely, but heal mucho health when they work. Running out of stamina kills more players than anything else except pure stupidity. Carry a food item for when you need a bit of stamina to make a getaway. The taverns often sell drinks that add 25 to stamina, and there's a tart apple salesman on the road between Rithwic and Cragstone that sells special apples that also add 25. Go into noncombat stance when not in battle, and you'll regain your stamina much more quickly.
More powerful attacks deal more damage, but drain stamina.
When you die, your corpse takes five minutes per level to dissolve. Be careful carrying great equipment at low levels, as you might die and not return to your corpse fast enough to reclaim your items. Or great for the lucky dude who just found amazing armor in a newbie dungeon. Be wary of using shields, especially big ones. Shields add much to your front armor level, but drain stamina very quickly, depending upon their weight.