I have an idea, what next?

First up: remember that most of your ideas are shit! Wait Wait, I'm not trying to be rude, I am just being honest and asking you to be honest with yourself. Most of the ideas we ever come up with are generally rubbish. The trick is ensuring you don't fall in love with them and you focus instead on the problem you are trying to fix. Think about that problem, think how many people share it, understand it as well as you possibly can. The next step is quiet challenging and most people skip it, jumping instead to solution mode. Stop and figure out a way to test your solution to the problem, ideally for free or for the smallest investment possible. If you can't solve the problem in your testing, as manual and clunky as it may be, change direction or pick another problem to fix. The most valuable thing you have is your time, don't waste it on shitty ideas.