I learned how to deal with bullying by becoming a bully. It probably wasn't the nicest thing to do, but by the time I was 16 people had stopped messing with me. I never experienced transphobic bullying (I've been outed, stared at, and snickered about, but I wouldn't consider that bullying) but I imagine the best way to deal with it starts with you yourself. You have to learn to just deal with the fact that some people are mean for absolutely no reason and everyone faces harassment in some way, shape, or form. Personally, I try to treat my situation like it's not unique. If someone laughed at you for a bad haircut, what would your reaction be? Most people would laugh about how stupid of a thing that is to make fun of because hey whatever your bad haircut isnt anyone elses problem and theres other people out there with bad haircuts too. Do you see what I' getting at?
People are dumbasses, man. You just roll with the punches. The best way to deal with a bully is to ignore them and make them feel as irrelevant as they really are.