While your vocabulary can improve by reading a english dictionary or simply reading a book. You can improve your pronunciation by also reading english dictionaries

If you want to improve grammar you should know about the subject-verb agreement: the verb should agree with the subject ex. They is laughing. The subject their is "They" they is plural (more than one) and "is" is used for singular (one). Therefore it should not be They is laughing. It should be They are laughing because are is plural and they is plural so its the correct grammar. If the subject is many the verb should also be plural(more than one/many)

For english grammer, I would suggest buying a grammer book. Something like Little Brown Book, or try this website, www.ablongman.com/littlebrown Vocabulary and pronunciation, then I would suggest a dictionary for vocabulary, listening to music and try to sing along and copy their pronunciation. Or watch TV and read the captions.