How to learn English and want to travel to America? I don't have any English foundation. Should I start with words?

It depends on how long you have to study. If you only study for three to five months, it is recommended to buy a book on daily life and travel terms. There are many such books on the market. You can take it with you when you go to America, and you can show it to foreigners when you can't talk about it. Of course, it is best to learn hundreds of common words, because when communicating, you don't have to say a complete sentence, usually one keyword will do! When studying, you'd better find someone who knows English to give you some general advice.