Welcome!
yeah the Library and and the newbie video in the sticky threads of New Members are a great place to start. I also watched a lot of Youtube videos of the various models I was interested in.
And my general advice since there is a lot of bs and lies in the seedy upper crust of ecig sales
Do not buy anything unless you know what Chinese model number it really is, whether it is a good and compatible model, what it should cost, and where else you can get supplies and parts for it.
In general we do not buy from "Name" websites that just sell "Name" model. However I do use Vapor4Life - that is a full featured slightly fancy vendor of KR808D-1. But I know a basic kit can also be purchased a bit lower at a multibrand vendor like LiteCigUSA.net. Some other good-price multibrand vendors are Liberty-Flights.com and Cignot.com
The most popular threadings
#1 510 by far
#2 KR808D-1
#3 901 and 801 (though 901 is similar to KR808D-1)
#4 4081
And I highly recommend you get manual batteries.
Some other things to know - small ecigs have short charge life batteries. Small ecigs cannot use the hotter parts that give bigger hotter drags.
100mah of battery charge is about an hour of moderate vaping. Small ecigs start around 180mah. Slightly larger small ecigs (120-130mm long) are usually 280mah. Fat battery models and mods that use removable industrial batteries are usually 650mah to 1300mah for the largest ones.