Check out google trends and see what the world is talking about, see what products are hot and in demand. Monitor retail channels and see what's selling well during a certain season and sell thsoe products. A good example would be those useless powerbands all the celebs are wearing, everybody wants them and they retail for £30, get some at wholesale and undercut the major stores to generate good income.
TechHawkz - Business & Recruitment Development Consultant
LinkSquare - Managing Director
http://twitter.com/LinkSquare7
Recruitment Solutions for SME's, entrepreneurs and startups at http://www.linksquare.co.uk