Lining up the wires, ensuring they’re straight m and making sure they’re trimmed to the same length will help avoid crossover too.

You can help straighten them on the square edge of a table, just press them between your finger and the table at the part that’s stripped from the insulation, then pull them over the edge applying pressure the whole time.

You can also look for the newer cat 6 connectors. Lots of brands have an insert that you can slot the wires in to before putting them in the housing, which helps a lot.