Are prepositions a nightmare for you? Never more! I'll try to help you, but you also have to work hard to learn them once and for all.
You can start by reading a general summary here.
IN, ON AT: Are you never sure about how to use IN, ON and AT? Here you have a very good explanation and an exercise. Would you like to try the BBC's Grammar Challenge to see how these prepositions are used to talk about TIME? Then click here.
MOVEMENT: You can read about prepositions of direction here and do an exercise too.
Do some more EXERCISES about prepositions of time and place here. You have more exercises here and here.
GAMES: Listen and pick the right picture in this game. Another game about prepositions here. A very nice interactive game here. Would you like to play basketball and practice your prepositions? Then go to this site to try.