#1 stamina tip is to get the well rested bonus. Simply sit down next to a campfire, and start building a proper home base. More comfort points = longer bonus. It is possible to have well rested last from dawn until dusk, then just portal home to sleep and refresh it. Aim to have the buff active at all times.

The swamp is basically your "well rested" stat check. The wet debuff ruins stamina regen, and well rested counters it.

Sweet mead super charges your natural regen rate for a few seconds and is generally good for an emergency bar recharge. Do beware that using stamina will pause the regen and waste the mead. Stamina potions recover stamina in any situation, and can even save you from drowning.