Zak: A lot of times, supporting your friend can just mean letting them know that you are there for them, accept them, and are willing to listen. In general there isn’t a whole lot you can do to help someone’s dysphoria other than be there to listen to them in an understanding way (which is to say, don’t dismiss their feelings) and, when appropriate, take their mind off of things (obviously if they are reaching out to talk to you, you should probably not immediately try to distract them!). If there are any specific areas of dysphoria that you feel you could help with, like helping your friend get or make a binder or going with them to shop for new clothes, that’s also great. I don’t know your friend’s particular situation, but I know many people who are still trying to figure themselves out long to buy clothes in a different gendered section than usual but feel too nervous to do so. Having someone to just go with them and make them feel less awkward can be a big help.
I know this advice is fairly straight-forward. Unfortunately there isn’t an easy fix or a well-kept secret to how to help someone with dysphoria. Sometimes the best thing you can do is just ask them how you can help.