I wear a waist/hip pack (I have this one from Dickies:
https://www.dickies.com/*****-packs/plaid-*****-pack/L10310.html?dwvar_L10310_color=GL#start=1) or a tiny crossbody purse (I have several, including this one:
https://www.baggallini.com/take-two...01-BG-B0001-NS.html?cgid=31&bvstate=pg:2/ct:r). Basically, the bag has to be tiny enough, and be worn close to the body, such that I never have to take it off on rides, or at restaurants, etc., and there's no chance of losing or forgetting it.
All that goes in it is:
- my phone (with My Disney Experience and/or touringplans apps - it also serves as my camera and my flashlight)
- "First Aid" kit consisting of some Tylenol (loose capsules, rolled up in aluminum foil so it's flat and takes up no space) and Band-Aids
- Hand sanitizing wipes, for quick clean-ups after the kids have touched every inch of every handrail, which is distressingly often!
Optional items:
- Disney VISA card, if going somewhere that has a card-based discount
- sunglasses, if weather-appropriate
- disposable Dollar Tree rain poncho, if weather-appropriate
- Ziploc sandwich bag for my phone, if going on any water rides
Some days, I don't even bother with a bag at all: I just wear a hoodie or a pair of capris with a couple of zipper pockets that can hold the same items, and go bagless. (Going bagless feels so free! To paraphrase Ned Flanders, it "feels like I'm wearing nothing at all!")
There are a thousand other things I could bring, but I've never suffered for not having them. I used to have to include a little phone power pack and charging cord, but I have a newer phone with better battery life now.