You can use either in most cases, but 'because of me' would probably be considered more formal. You can use 'thanks to me' in negative examples as well as positive ones if you want to sound a bit sarcastic, which English people often do.

Well, if you knew Chinese, I would say, "thanks to" means "多亏了..." while "because of" means "因为...". But I assume you don't. So anyway, "thanks to" is a possitive phrase which means you can't not use it in a bad case; while "because of " is a neutral phrase which means you can use it in either case. For instance, you can't say "He is sad thanks to me", but "He is sad because of me" is OK; or "I lost my wallet thanks to my carelessness", also, "because of " here is acceptable. If you say something positive, you can use either of them, like "I got an A in math thanks to/because of my hardwork". Got that?