Running ethernet cable looks simple but there’s a right way and a wrong way. The wrong way: stapling the cable tight, pulling it around sharp corners, kinking it, running it too close to power wiring. All of these will cause you to fail certification testing. The right way: follow the minimum bend radius (4x the cable diameter - roughly 1" for Cat6), keep staples loose enough that the cable can move, maintain at least 2" separation from power wiring (more in commercial).
Termination: untwist as little as possible when punching down. The twist pairs are what give Cat6 its noise rejection. TIA-568 allows up to 13mm (0.5") of untwist at terminations. Use the right punch-down tool - a 110-blade punch-down tool with the spring-loaded mechanism.
Testing: a wiremap tester tells you if the wires are connected correctly but doesn’t tell you if your run will actually pass Cat6 specs. For certification testing, you need a cable certifier like the Fluke DSX or Versiv series. These test insertion loss, return loss, NEXT, PS-NEXT, and all the parameters that actually affect performance. Commercial jobs need certification testing with printed reports.