Basic check list
1. Read the forums and take in information until you can identify the following.
Pump, Res, Rad, CPU block, GPU block, barbs, compression fittings, Push pull setup, tubing sizes
2. Understand the basic functions and order of a loop.
PUMp > Rad > Block >Res > back to pump
3. Get a good idea of how you want to setup the loop inside your case
Top or bottom mounted rad, where you want the pump to go, Bay/Res pump vs. Stand alone pump. Get a good idea of your case size and do some drafting and post on here to bounce ideas off the community.
4. Plan out your parts list or pre-made kit and post on here for advise and planning.
5. Learn how to install, bleed, leak test, and pre-test all equipment before installation.
Those are just the basics to start with but until you can understand that I wouldn't recommend ordering anything.
Just jumping into watercooling can cause some expensive mistakes.