When I first got into RDAs I had been off and on smoking and vaping for about a year and a half. All of my vape friends were using RDAs and had sweet mods. I decided to jump on board too and I haven't looked at a cigarette since.
My biggest piece of advice is to read reviews on every RDA that you come across. Look for something easy to build on first too, such as something with 4 post holes or such. 3 post holes are easy to build on too, but take a little bit more of a learning curve.
Get quality cotton, a few different gauges of kanthal, and a decent ohm meter. You always want to test the resistance before you build. You can get a lot of that on Amazon, especially the kanthal for dirt cheap. Small wire cutters and small pliers are a must!
Lastly, watch tons of tutorials on youtube if you haven't already. Its super easy once you practice a few times, and if you buy 100ft of kanthal then you have some to spare if you mess up.