I'm pretty freshly diagnosed, but I'd say the best thing is allowing yourself to slow down and take a break. If you need to lay down in the middle of the floor, go for it. Give yourself the same kindness you would give to someone else in the same position.

sleeping well. at the same time every night, it sounds very over-said but it genuinely helped me so much. (many bonus points if you raise the head of your bed, search that up, trust) drink mix-ins with (a lot of) salt compression socks for school/work (or just long days out) water water water (with salt) doing both raises your blood volume which makes more blood reach your brain :) (don't do this if you have hypertension) maybe ask your doctor for a stimulant? i'm on focalin for adhd but it helps my pots symptoms a lot. sitting down in the shower & taking fast showers carry those pop & shake ice packs, mostly on hot days i like to wear thin fabrics, helps if it's hot outside if you have trouble with your stomach after eating (because of pots) i suggest doing 10 sit-ups before you eat (hear me out) doing this gets more blood flowing to your abdomen and makes digestion preform better if you're in school, talk to your school about having constant access to water (and the bathroom) & salty snacks. & having access to lay down in the nurses office if needed, (or even just to lay down in class lol). try not to lay down too much, try to increase your stamina with standing, it'll be hard but unfortunately it's necessary :)