The single most important thing when building your own system is to be disciplined about static electricity and not discharging on vulnerable microcircuits.
If you go to NewEgg and read reviews on Mobo's, you will see 1 star reviews on boards that were "DOA" by someone whom professes "High Technical Knowledge." This is the Dunning-Krueger effect in action.
Years ago, an SGI tech came to our office to install an SGI workstation. He took immense care with grounding himself, and explained that at SGI 35% of all returns were from static events by highly trained technicians with advanced degrees!
If you watch YouTubes of guys building systems, you can see them handling motherboards like books. Grabbing them with their full hand, fingers all over black chips, and the under sides of the board. This is stupid!
My personal method does not use the little static conductive wrist tethers. BUT, I take my socks off, and work on wood or stone floors. No rugs. And especially no plastic floor protectors. If you must build on a rug you should neutralize your charge every time you move your feet. How I do this when handling a motherboard, is to find the 24 pin slot where the main PSU connects as there are capacitors after it with much higher resistance to the static charge you may be storing, and I place my fingers on as many pins as I can touch, then I touch a conducting part of the next component I am handling at the same time. If it's the CPU, I will touch the shielded outer surface. If it's a HDD or optical, touch the outer sheet metal. Never touch a chip surface directly if possible. This technique equalizes the charge. It doesn't necessarily 'earth' the charge, but is adequate for assembly. Do this often for each new part you assemble. Once the motherboard is in the enclosure, attach the PSU to the mono and use the outer sheet metal of the PSU for future neutralizing, or the case chassis, since all 3 are now 'grounded' together (not necessarily Earthed).
Take your time. Assembling my last machine in 2015, it took about 4 hours, not including unpacking. That build only had one DOA, a HDD. The first DOA component I have had over ~10 PC builds.
If this is your first build, you may choose to "breadboard' the build. This means building up the mobo, RAM HDD and PSU only to confirm the core parts are working. I never do this personally since it requires you to handle everything at least twice, doubling your chances for an error.
Don't over tighten screws. If the screw goes in with difficulty, ITS THE WRONG SCEW. If you have a water cooling unit DO NOT OVERTIGHTEN! See all the bad reviews about cracking plastic and coolant spilling out? Housing snapping, etc? These people are over tightening screws and bolts, deforming the material and causing stress fractures. It's a computer, not a Baja Racing vehicle. Slightly hand-tight is tight enough!
The most nerve-wracking procedure is installing the CPU in to the slot on the MOBO. Sometimes the securing clips require a lot of force to close. Force is usually something to avoid at all costs, but some clips, like the i7 clips can be scary hard to snap down.