ID, keys, door clicker, cell phone go in one pocket on the jersey (middle) because you don't need them often. Chapstick, cue sheets, food, go in another pocket (RH side) since you need access to them. Jackets or vests go in LHS pocket since you need access but less often. Don't put keys or valuables in a pocket that you will be digging around in. I've never had anything fall out of a jersey pocket on its own but I HAVE pulled out items when reaching for something else.

Seat bag is for spare tube, patch kit, multi-tool, tire levers. This keeps it nice and small.