The internet is full of "do it yourself" videos, and it is not always clear when to try it alone and when to pick up the phone. The decision comes down to risk, tools and time.
Simple jobs like hanging a picture, changing a bulb or tightening a loose screw are perfect for DIY. They are safe, need only basic tools, and if something is not perfect it is easy to fix.
On the other hand, anything involving electricity, pressurised water or structural loads calls for caution. A mistake in an electrical connection or a pipe seal can cost far more than the service call you saved.
Consider time and tools too. A job that would take you a whole weekend and requires buying expensive one-time tools is usually better handed to a professional who finishes it in hours.
The simple rule: if you are not confident you can finish safely and to a good standard, or a mistake could be dangerous or costly, it is time to call for professional help. You can always start with a quick phone consultation.