Steps before "Validating my idea"?

Hi everyone, I'm at the stage where I have the seed of an idea and plan to go Lean-Startup style and try and test/validate the idea before I build it. Question is - are there any steps I should do BEFORE that? I imagine that writing it down clearly is a good start (some kind of business canvas?) - and as an added question, is there a service/toolset that provides all the tools needed right from writing the canvas to the end of idea validation (like landing page, email capture, graphics and copy etc)? Many thanks all Matt (Notes - Idea is an app/web service in the household expenses/life admin niche)