Here are some techniques that work for me:
1) Try to express feelings with music. Think of people you like, people you hate, things that made you happy or things that made you sad. Or close your eyes and imagine sceneries in your mind. If you have a clear picture, keep it present in your mind while filling it with music.
2) Make music when you don't really have the time for it. Had my best ideas when I was in a hurry - made naught but crap when I sat down to make music because I had enough time.
3) If you want to make a new tune, take a few minutes to come up with a name for it first (you can still alter it later). But you can almost be certain that you will never finish a tune if you save it as "new_idea_34" or "test_13".
Come up with a nice name for your tune and apply 1) fitting to it.
4) Listen to tons of other music for inspiration.
5) Never save up any special sound or effect for another tune. You will never create that tune, so be lavish with your instrument base.
6) Never re-use drumloops, or sounds that made one of your previous mixes special. Try to do something different every time, and find something for each tune that will make it unique.
Hmm that's about what I can come up with for now... hope it helps
