What am I able to repair without trades

[Jeremiah Dunakin]

So I am half way handy. I can do a lot of basic plumbing and electrical things.My question what things am I allowed to do? Can I change out flickering light switches? Run new plumbing lines to faucet/ tub. The rental I have I remodeled by myself and lived in it for awhile. I gutted bathroom and kitchen and remodeled them. I did have electrician do some wiring for me. I had them install some new outlets for me. Can I change out existing plugs and outlets or fix cracked pipes. I live in Michigan