1. Replace "too" with "as well."
Good: I'm a General Course student as well.
Bad: I'm a General Course student too.
2. Replace "very" (in most cases) with "quite" and liberally pair "quite" with any adjective you like, especially "good" and "nice."
Good: That Indian restaurant is quite nice.
Bad: That Indian restaurant is nice -OR- That Indian restaurant is very nice.
3. Replace "Thanks" to bus drivers or cashiers with "Cheers." This assumes the bus driver acknowledges your presence or answers your question, a weak assumption.