Hi Terry It's difficult. There are so many to choose from! Obviously it depends on you. Every student is different. However, you might like to think about five different aspects. For example, quite a lot of students that use italki prefer to use a book (or written websites etc) for developing their grammar, writing and reading, watch and listen to films/TV/podcasts for listening, and then use the italki lessons or language exchange to develop speaking. Probably you will need a combination of these things (most people do), and the balance between the different parts will change as you develop your language skills. A very good book for studying grammar is English Grammar in Use by Raymond Murphy, and I find the Collins English for Life series of books very good. Especially the ones that focus on speaking.

Compelling Conversations by Eric H. Roth and English the American Way by Sheila MacKechnie Murtha M.A., Jane Airey O’Connor M.Ed. are good options. If you would like to help with your spoken English, feel free to send me a message, I am a community tutor for English here and I would like to help you reach your learning goals.