Oh man, fantastic questions. I was cartomizer for a long time, and then broke into the atomizer world like 5 years ago. How you go is all dependent on how you like to vape. Small and discreet? Huge amounts of vapor? It sounds like you're a mtl (mouth to lung) so you still vape much like you would pulling on a cigarette, right? There's also direct to lung, where you vape like you're breathing. No filling the mouth first with vapor. If you've been doing cartomizers, then let me tell you, moving up to an atomizer is like crazy more flavor! Going up to 510 threading really opens up a lot of possibilities for you. If you want to start out slow, then go for one of the starter kits. Having the whole kit all there in front of you ready to go is so much better than starting off with just a stick battery and trying to figure out what to put together with it. Also, stick to mtl for the beginning. DTL can be harsh at first for someone not used to warmer, fuller vapor. Now, if you want to jump in with variable wattage but stay small and convenient, then something like the Eleaf Pico is beautiful. In the kit they pair it with the Melo III mini tank, which holds 2mls of liquid. Really nice, solid little mod. Goes to 75w. I am a mtl (just personal preference) and I almost never vape all the way up to 75w, though once in a while I pull out one of my 150w monsters just for all the clouds of vapor. The Pico is just really small and convenient, tuck it in your pocket and go. The Melo tank gives beautiful full flavor. However, just for novelty, I paired my Pico with the new Atlantis Nautilus X tank, which is 2ml like the Melo but has this new airflow system that I wanted to try out. I am really surprised at how nice the Nautilus X is. Good full flavor and I find the top mounted airflow regulator absolutely non-leakable. I have not had a drop of fluid leak from it. Ask some more about your preferences as to size, power, flavor, all of it. There are amazing vapers here who know huge amounts of stuff. Maybe this helps a bit to give you an idea of what's out there.