Avoid stress.
Get regular massage of neck and shoulders. Tense muscles in the neck can trigger it.
Wear a scarf that can be pulled up over your face if it's windy.
Avoid sudden changes I temperature.
Relax your face when brushing your teeth. And clean them meticulously because you do NOT want to sit through a filling or extraction, believe me. I'm lucky to have had a fantastic student dentist who was absolutely fascinated by it as he had never actually seen a case of it and was very very careful with me so as not to provoke it unless absolutely necessary. Most dentists just shrug and say there is nothing they can do to avoid triggering it but that's bullshit, they just cba.
Don't chew your food too vigorously.
Avoid any impact to your face and any sudden impacts or jolts. No jumping off anything. Be aware that attacks may happen at any time. I've had one in the 3rd lane of the M25. Not fun.
Take the highest possible dose of painkillers before seeing a dentist and eat before the appointment because you may not be able to for a few days afterwards.
Keep painkillers on your person at all times. Good ones. Paracetamol will not cut the mustard. Keep them in your bag, in your locker, on your desk, in your car and in all rooms of your home. If you haven't eaten, take with yoghurt or a fuck ton of full fat milk. Your stomach will thank you.
Drink alcohol as little as possible. Your liver and kidneys will have quite enough to be getting on with, with all the meds.
Use a flannel when washing your face. Do NOT splash with water to rinse. Even warm water. You'll regret it. Also approach swimming with extreme caution.