What should I do after I have an invitation letter?

With the invitation letter, it is only a small link in the whole visa process. More importantly, prepare your own materials, such as employment certificate (or company), credit and financial proof, and the reason for going to the United States should be reasonable, so that visa officers don't doubt it. So your real purpose can't be revealed, or it will be over soon. Your English will be of great help to you in coming to the United States in the future, but it will have little effect on your visa. Of course, talking is better than nothing, at least convince the visa officer that you have the language ability to go to the United States. You can apply for a visa at the US Consulate in Guangzhou with your Guangdong temporary residence permit and ID card. Visa fees will change constantly. You can check it on the website of the American Embassy in China. Several people have answered other questions upstairs.

Friendly reminder: American visa is the most difficult in the world. You must go all out and don't take it lightly! It is best to spend some money to ask a senior intermediary to sort out the materials and fill out the visa form to avoid mistakes. Visa has a little Kanekin's law, that is, to succeed, all links must meet the requirements, and the key to success lies in the weakest link. Finally, good luck!