Toolswise i recommend buying this, covers all your needs from coil making, to checking your tank's ohm's which is more important if you use a mech mod. There is a 20% off code XMAS. so the cost will be £16 and pence with free postage.
https://www.newvaping.com/products/coil-master-diy-kit
Regarding best RTA's 2 i reccomend are duel coil but as easy to build and give fantastic flavour. 1. The Advken Manta 2. The QP designs Fatalty M25. The Fatality is 25mm though. Manta wise i have a brand new gold colour with the resin glass section going spare I got about 12 Manta's plus 2 spare in gold. I may have a silver one spare as well, i need to check the spares cupboard first.
Don't forget you need cotton to make your wicks. as well as the tools, maybe get some wire types as well.