First tiny freelance job questions

I don’t know what to charge, how to invoice, or what kind of contract I need to write up. There is lots of info about this around the Internet, but it seems to be aimed at more established developers doing larger projects in higher cost of living areas. If I walk in with a 10 page contract asking for $300/hour they’ll probably politely decline. That in mind, does anyone have any advice on how to proceed?