ok so the first question has to be are you after a mouth to lung kit so just like smoking with a tight draw where you inhale into mouth and then take down to lungs. these kits use much lower wattage like 10-14watts.
or a direct to lung kit where you inhale directly into lungs a bit like a bong if you ever dabbled. this gives much bigger clouds and uses much higer wattage. depending on tank and coil it can vary from say 30watts to 150watts.
this is worth bookmarking for future reference
POTV Vendors & Recommended E Liquid Suppliers
there are so many kits out there from small pen types to pods which are bigger upto box mods which either have an internal battery or removable 18650 batteries which you charge on an external charger.
have a look at some of the suppliers on post 5 of my above link but always ask here first before you buy as we usually have disccount codes or know the cheapest supplier.
if you have a vape shop local to you you could go in for advise and ask about the different kits but there are some that just want to make a quick sell so let us know roughly where you live and we can advise on decent helpful shops.
the latest 2 i bought was the vaporesso PM80 which is a pod system. cheapest price ive seen is a tenner less than i paid for mine
https://www.rainbowvapes.co.uk/collections/hardware/products/vaporesso-target-pm80-kit
good luck and ask as many questions as you need as it can be a bit daunting at first. weve all been there so know its brain overload.
ps. ive been vaping custard with diacetyl for the past 5.5 years and my lungs are clear as a non smoker even after almost 40 years of smoking.