1. Make sure you're not working in a static environment. Don't work on a rug.
2. Make sure you're static-free.
3. Don't force anything. Everything should clip into place without much force.
4. Make sure you're placing parts into the right slots.
5. Don't over-tighten the screws on the motherboard.
6. Don't drop your parts. Don't be clumsy.
7. Don't get mad at your parts just because you can't get them to work right away. A unintentional punch or brutal attack can easily result in breaking it.
8. Get a PSU from a reputed manufacturer.
9. Best to test parts individually and every step of the way instead of putting it all together right away and then test.
10. If you're water cooling, test for leakage. For custom water cooling, also rid the bubbles.
11. Don't overload your motherboard with fans and fan splitters.
12. Don't touch your CPU pins.
13. Don't spread too much thermal paste (if applicable).