Welcome to ECF. Great place to get the info you need yo!
Most would reccommend you get one of these:
Electronic Cigarette - Starter Kits - Riva 510
Electronic Cigarette - Starter Kits - Joye eGo
(click the discount code tab for 20% off)
They are both 510
threaded
devices so if you want to get any additional attachments they will need to be 510
threaded also.
If you want one that's cig size (about superking size) get one of these:
Smokeless Image | Only The Best Electronic Cigarette | Starter Kits
use code 'heatwave' for 23% off but not sure if it's still active anymore.
The volt is a Kr808D-1 threaded unit so you will need to get Kr808D-1 threaded attachments such as cartomisers.
With the ego or riva, if you get a 650mAh battery one it's not much bigger than a superking, just fatter, about the size of a big cigar and should last upwards of 6 hours.
The volt should last about 2 - 3 hours but is automatic so it'll feel more like a cigarette in that there's no buttons to press.
That's a really limited selection but honestly, the most reccommended units for their performance and value for money.
Next comes eliquid. 24mg is considered high nicotine content and some suppliers only sell 18mg or lower. 18mg should be fine but if you feel you'd need it 24mg will be stronger. As a general rule you only absorb 10% or less nicotine and it's Xmg per milliletre. So 24mg is 24mg per ml and there's about 20 drops in a ml. You'd get about 1.2mg per drop (very roughly) which is a few puffs really and would absorb around 10% of that, so you'd end up with an estimated 0.12mg of nicotine per drop absorbed. So you can dose yourself off how many cigs you had I guess very roughly.
You tend to have two options for liquids. They are pg or vg based. Pg is stronger on your throat and retains flavour better but produces less vapour. Vg is less flavourful, easier on your throat and produces more vapour. Why most prefer a mix of pg and vg to get the best of both out of their juice (flavour and vapour and throat hit). The higher your nicotine content is the stronger it will be on your throat too.
You have options for what to use on your units too. You can use
cartomisers which is probably the easiest portable solution as you just put liquid in the filling (about 1ml if it's regular size) and vape it until it's getting dry then put more in it.
You can use an
atomiser which doesn't hold very much liquid at all but can be the best performing way to get nic if you don't need it to be portable.
There are also
tanks which hold much more liquid but their performance can be shaky and aren't the easiest to get going. The most portable but possibly the most difficult to get working reliably.
Hope that helps a bit. Shoot any questions you want, everyone here would be glad to help
Vape On 
