I’ve been “vaping” for over a year and have completely quit real cigarettes as a result. I don’t reccommend the ones that look like real cigs; the quality tends to be poor and because the cartridges are not interchangeable they tend to be more expensive. Instead, go for something like an Ego-Vision kit, which comprises a longer-lasting battery with a refillable tank. Lasts much longer, cheaper to maintain and you can get a multitude of different flavours of liquid.
Nicotine strength is a factor too, and depends on how many cigs a day you normally smoke. If you’re a light smoker (10 or less a day) you won’t want to go above 12 or 14mg/ml. A very heavy smoker might need to start at 20–24mg. And if, like me, you’re a “chain-vaper” you can get very low or even zero-nicotine liquids.
You can get quite in-depth with advanced kit too. Best thing to do is join a vapers forum that’s appropriate for the country you live in, and you’ll get plenty of reccommendations for good businesss to buy from. Also lots of advice if you have technical difficulties.