you can always looks around for people who need help on things (ME) or look for community builds.
:o Need help? Perhaps I can be of service?
Also, write down stuff. I had a list of like 10 things last year that I thought were cool. In school or whatever, you think of something, just jot it down on a paper.
Hmm... What are you interested in though/ what do you want to make/ theme? Modern, space, Medieval, Zombies, ETC.?