Thanks very much everyone. I think I will start trying to compose more orchestral stuff.
Also, in reply to Annon, with electronioc music, I don't spend much time at all tweaking the preset VST intruments that come with Cubase for my music.
I could also, like you said spend a bit more time working on parts. I think I have got in a bad routine where I find one good theme, then make crappy support tracks for the theme, and then leave it.
I have one question. How do I know which alterations to synths, (such as filters, cut-offs, and the sound itself, etc) would work for a paticular type of music. I have trouble seeing how a basic square synth would work in a certain situation as opposed to a saw synth. I hope that makes sense.
Thanks again for all your replies, you have raised my composing confidence.