Just do small jobs to gain confidence, change taps, fix leaks under sinks etc. You can't go far wrong IMO and then progress to float valves, fix toilets etc., just go slow & charge enough.
What are you confident in doing? Start there, once you do it once you'll be sorted. I was the same, no confidence, sometimes didn't know what to do, couple of good people here have helped & shown me a few bit I'd never have known about. It's all about confidence & time to gain experience.
You gotta start somewhere but get Insurance just incase.
Good luck
