1. Food, food, food. No good food, no stamina. Get the best your biome can make.
2. Rested bonus is the second most important one. Without it, your stamina regeneration is really low. The wet debuff never really hurt me that much, since my rested bonus clearly had the upper hand here. Without it, though... Yeah.
3. Depending on your "class" you need different food builds. HHS for tanks, HBS for melee DDs, HSS for bow and arrow. As a tank you really need to be good at managing your stamina levels, but it usually should be no problem, if the above conditions are met.

H = Health
B = Balanced
S = Stamina