If you speak English and you don't know what to say, you need a bigger vocabulary. Obviously the best way to improve is to study with a teacher or in a group but if you can't do that, here's my top tip for you: Read!
Specifically read news articles: the language they use in journalism and is sometimes difficult but it's often very rich and colorful. Uses a lot of very natural English idioms. So, if you want to expand your English vocabulary but don't have a teacher, start reading news articles (newspapers and/or magazines).
YOU ARE READING
English Grammar Tips (I)
Non-FictionGrammar, vocabulary, interviews. Everything you can imagine, ...
