My goal was simple. I wanted to create something, have it made, and be able to use it to solve my specific problem. I didn't go into this venture expecting riches, accolades, or reknown. Although, don't get me wrong. If those things should happen, I wouldn't shove them away. But I wasn't motivated by those things. I just had a need that I wanted filled. If I had to make it myself to get it, then so be it.
Sometimes the best ideas come from necessity (I think I read that somewhere from some guy). Anyway, the place to start is with what you know and what you know is lacking. Once you think you have hit upon an idea, share it with a couple of people you trust will give you the hard truth. Not someone who enjoys ripping you up, but a trusted friend who will lovingly point out where you might have erred and succeeded.
The first idea I had was rejected by the two people I trust more than anyone - my mother and my husband. It was hard to hear the truth about my original idea: it would be too expensive to make and therefore too expensive to buy. But, I'm getting ahead of myself. Don't worry about cost, practicality or logistics of getting your idea made. Just let your mind open to the possibilities first. For those familiar with the concept, this is the "brainstorming" stage. Focus in on what you know and begin brainstorming ideas.
You see, it was because of my first failure that I was able to come up with my second and third failed ideas that lead me to the successful forth idea.