Safe to DIY
Replacing a switch, outlet, or fixture, after killing power AT the breaker AND verifying with a non-contact tester (around $15). Use the tester. Always.
Always electrician
Anything inside the breaker panel. Pre-1970 aluminum wiring. Repeated breaker trips on the same circuit (means a short somewhere). Anything inside a wet area without a GFCI.
Why it matters
Electrocution is fast. Bad splices behind walls cause house fires years later. The skills you’re missing are the ones that prevent both. Pay the $200.