I start! With a stock plug and work it from there.
I purchase wire on a roll and cut my own. Normally, it turns out good. Once in a while, a wire is to long. EZ fix.
I purchased a MSD wire crimper. Cool tool.
I forgot to mention that. If you are going to make your own wires (I think it’s the best way to do it) you’ll need good crimpers. Crimpers designed for plug wires.
I have the Moroso crimper, but it’s getting plenty long in the tooth, so I may replace them here soon.