However, after diving a lot into Lean Product and UX Design, I have learned that the hardest part is finding problems worth solving. In my opinion, being able to discover problems that have terrible solutions and workarounds are really where good ideas are spawned, then "hypothesized" and "validated".
Also, for helping to formulate your ideas (I am assuming a business model), it has helped me to use a business model canvas. I like the "lean" one from http://www.runningleanhq.com and there is a link to one from Steve Blank's blog article: http://steveblank.com/2011/09/22/how-to-build-a-web-startup-... and a good slide explanation: http://steveblank.com/2010/11/15/creating-startup-success-cu...
Hope this helps.