"Always burn your old projects on a disk.Never throw away anything creative,sometimes when you look back - things can sound better than they sounded in the past."

The golden rule! Old ideas can really sound very different after a while, it is always best to keep them, and go through them all when you miss the inspiration.

An absolute golden rule

I agree - things can sound very different when listened back from another perspective

Golden rule...If your song you are composing doesn't work for you at certain time , leave it off (and backup) and get back to it after some time...Most likely you will find a better solution and finish the song easier and better!