Well the best place to start is by figuring out an RTA that might suit your vaping preferences, and you are getting some good suggestions. I think some of your tanks might have build decks, but they tend to be small, difficult to build on, and really don't provide "the best" RTA experience since the tanks are really designed primarily for drop in coils. With that said, since you have built before you could try using a build deck in a tank you have, but most folks wind up a bit disappointed in the experience.
I started with single coil, large decks. I know the Engine series of RTDAs are well liked as they are easy to wick, and don't tend to leak, and give great flavor. You can get a single coil Engine. A lot of folks swear by them, although I believe the juice well is smaller. If you want to go to a true, larger capacity RTA, yes, watching some reviews (more for figuring out how to build them) is a good idea, it will help you figure out what builds may work well for you, wicking and etc., and what things to watch out for. Also, plenty of folks will be willing to help along the way. LOL, my first build was completed with ECF cliffnotes, I don't think I would have gotten it done otherwise.
Basically, you need wick and wire of your choice. I think primarily people are using cotton and rayon these days (lots of options). I personally find rayon more forgiving than cotton and I don't have to replace as often as it withstands heat better than cotton, and it's a relatively forgiving wick. But plenty of folks love and use cotton as well, plenty of types to choose from.
If you feel you need it, a coilmaster kit can be helpful, but it's not actually necessary. Plenty of folks test their build on a regulated mod, although I do enjoy having an ohm's reader to build on as I have a fine motor tremor and having a stable base is super helpful (for me). I coil, wick, fill and test the tank on it, before transferring it to my (far more expensive mods). I've leaked all over mine several times, and it just keeps on going. An ohm's reader isn't necessarily going to be more accurate than a mod at reading resistance, though, so if you feel you don't need as many "tools" as are in the kit, really you just need something you can use to wind around that you know the diameter of. That could be as simple as a screwdriver. Ceramic tweezers are useful and I actually use most of the tools in my coilmaster kit, although they aren't super high quality, they are useful.
Finally, you may want to check out steam-engine.org, it will give you the ability to select the best wire for the vape you are looking for (e.g. stainless steel or kanthal, what gauge of wire, and help you "target" the resistance you want to build the coil. But, you can also get premade coils of different metal types and resistances if that appeals to you. Coils can last a long time. Wicking is typically more frequent.
But overall it is much less expensive to rewick with a bit of cotton or rayon, if you are using super sweet or super dark, gunky juices.
There's kind of learning curve but given that you've built before, you really should decide what you "need" to get started and go from there.
Best of luck
Anna