How To Help

The first thing you should do is ask how you can help. They may or may not know how yet, but you can figure it out together. Don't be offended if they tell you not to do something or that something you're doing is making them dysphoric/bothering them. Listen to them and help them the way they want to be helped. If they don't know what they need help with, then you can move from there. Do research and brainstorm ideas together. 

It is vital to respect them and their identity. If they want to go by a new name, call them by it. If they want to go by different pronouns or want to experiment pronouns (or if they frequently change), respect them. If you accidentally deadname or misgender them, don't make a huge deal about it. The best rule of thumb is to apologize, correct yourself, and move on. It can be distressing for the trans person for a big deal to be made out of it. Always respect them and help them feel comfortable as themself.

You can become an advocate for the trans community. As a cisgendered person, you have more rights than them. You don't experience that kind of discriminations. If you see an issue, help fix it. You can help change these laws set in place that prevents trans people from having equal rights.