I'm a very intuitive, stream-of-consciousness type of person when it comes to composing sketches, it's all very neurotic for me.
I'm also an improviser, so one of the best methods you should utilize if you're playing it it on your piano, is to RECORD IT.
Do you study music? How long have you been playing? just wondering, that could help to specify further.
Composing is a personal experience, which has personal significance to the composer, so it will vary person to person. The best way to become as efficient as possible is work out the way you think and take advantage of it.
But for instance with recording, the more you practice transcribing your improvisations, the better you'll get.
If your'e studying theory, you'll start to automatically say e.g. "that's a minor 6th", "that's a major 2nd" and so forth.
Hope this helps, let me know!
