I have weird and ultra-specific habits for what I take and where they go on me.
Front left pocket is always cell phone (and occasionally chapstick), front right is keys, back right is wallet and if we're spending a full day at a park the back left will be a water bottle. Anything more and I feel like I'm just bogged down with too much stuff. Anything less and I'll have constant waves of "Oh my God did I lose my ____?!"