Re: @Steven Smoke on the water vapour
If you're interested and in the UK, I recommend that you look at Vapeland and Liberty-Flights. If you do a Google search for e-cigs, e-cigarettes, etc. then you'll find loads of links and you'll easily be able to tell which are 'tabloid' type sites and which are the serious forum type of site.
My personal recommendation is that you start with the plastic-ciggie ones from Asda and learn how to take the end cap off the cartridges for refilling (hint - use a short stubby screw and a pair of pliers). Get 24mg strength e-juice and dilute it with glycerine, from the high street chemist, to knock it down to about 18mg strength, or whatever. Use a syringe or a needle capped plastic bottle to inject the e-juice down the side of the casing. I use a strong 'pipe' flavour mixed with caramel flavour - it's all personal taste and experimentation.
If you get fed up with the regular recharging and refilling with plastic ciggies, splash out on a twin-pack of eGo-T style of systems from Vapeland. They supply e-juice as well, as do many internet based sites.
I have no connection with any supplier of e-cigs, etc. This is all my personal experience and opinion.