Assuming it is a web startup. Build a content website on something you consider yourself good at. Try to get users, make money through adsense, put up analytic

Assuming it is a web startup. Build a content website on something you consider yourself good at. Try to get users, make money through adsense, put up analytics and test it out. You would learn a ton about how(and what) works on the internet - and possibly be making enough by the time you are ready to quit to bootstrap your startup .