You and a million others want to start making money with their hobby, photography. So I would not get my hopes up. That said, it’s more of a business undertaking than a photography undertaking, and every genre is different. So start with what your of photography business genre you are interested in… then you might get some useful advice.
Not sure what you have committed to, but I think you will almost certainly have to use flash if there isn’t some unusual lighting going on. Parades are moving. It is dark. I would not think they have lighting even as good as a high school gym for indoor sports. The lighting is the key. Have you used flash before? You will need to understand how it works at distance. You will need to understand flash sync speeds, etc. You really need to do some testing beforehand, but I doubt you can recreate exactly what a parade will entail… slow moving vehicles will people standing on it moving around… bands marching down the street, etc.