Get yourself a canteen, and fill with water you trust, before you leave for the march; carry that, and use it to drink from. Two is better. Glass is bad. If there are meds you must have, put at least 24 hours’ worth in a small container and keep that on your person. Many surplus canteen covers have a pocket designed for this.
Add a bandanna to your gear (wet, it can help you breathe despite some forms of tear gas; it’s also good for wrapping e.g. a sprained ankle or washing pepper spray off your face). Make it one you don’t need to keep. Sew a pocket into a second for that container of meds mentioned above, tie ‘round your neck and you’ve got a secure carrier.
If you wear a scarf, wear one with handwarmer pockets.
Wear shoes you know and trust — not new, and please no spike heels. Dress for the weather — if it’s gonna be cold you’ll want several light (adjustable) layers rather than one or two heavy (and mobility-impeding) ones.
On the Sharpie “march tats” — if you carry a phone, and I would not carry my real one, but you’re going to want one with a camera capability — put your ICE (in case of emergency) in a “contact” by those initials in the phone — put an icon on the homescreen — *and* somewhere EMTs can find (back of your hand, across the arch of your foot) in case you’re unable to speak.
