My first bit of advice is this.
The e-cig has developed fast and dramatically. The latest products are better than ever in terms of efficacy and reliability.
What has not moved so fast is the products the big brands will sell to you.
Not only do they claim to be 'the best' or 'top rated' and that one refill is 40 cigarettes etc. but they also have bribed and distorted the internet so the real picture is now hidden away in the corners of the internet such as forums.
To get started, you just need an e-cig and liquid. If you are not refilling, chances are a) the product is going to be very expensive and b) the people selling it to you are not interested in you quitting smoking, only their pension funds and salary bonus.
If you don't ask about what you plan to buy, you could find yourself $500 down ($800 in my case), still smoking and getting more unhappy by the day if you have thrown those cigarettes in the trash.
Nobody wants to waste $500. Most people feel cheated out of even $100.
If you are ready to go and don't mind not hitting the exact mark straight off with a small investment of $30, $40 or $50, then I would recommend.
Innokin T18
joyetech AIO
eleaf iJust start
Kanger Top Evod or Subvod
I saw the Top Evod for less than $15 recently. I know one company selling something similar to this for "only" $119 last month.
That's how bad it is.
Good luck.