If you are looking for two piece, a thing that looks like a filter plus a battery that's thing, looks kind of like a 100 cigarette when the filter is screwed on, the KR808D-1 e-cigarettes are like that. Good products are available from nhaler.com, vapor4life.com (their Vapor Kings), vaporsetc.com and many others. The standard "808" battery runs a couple hours between recharges, while something called the XL or Mega battery runs about 50% longer (and cig plus filter, called a cartomizer, would then be about like a More or other 120mm cig). A typical starter kit, two batteries, charger, and couple of cartomizers, runs $30 - $50. Add in a couple of additional 5 packs of prefilled cartomizers and you'll be around $45 - $65. (all the online vendors I mention have discount codes)
If you smoke often, the XL or Mega battery makes sense. If it's much under a pack a day the standard 808 batteries would likely be fine.
There are both automatic and manual batteries. Automatic is suction operated -- turns on when you inhale. Manual has a little button on the side. I use both but find automatic easier to start off with. Some people will complain about automatics -- many of them haven't tried current generation 808 products.
If you smoke more than a pack a day, the eGo/Riva/510 family of personal vaporizers (PV) is another solid choice. In that case liberty-flights.com generally has really good pricing (their Riva 510 starter kit is $30 after the online discount code). With them I use what is called a Boge 2 ohm 510 cartomizer (the filter thing). They will be manual units (button on the side).
For something that has cigarette shape, extremely simple to use, an 808 kit with prefilled cartomizers is hard to beat.
For liquid, different strengths are available, expressed as mg/ml, often shortened to mg. A full strength smoker typically uses 24 mg, may need one level higher or lower. A lights smoker typically uses an 18 mg, may go one up or down. As an ultra lights smoker a starting point might be 12 mg/ml strength, though it would be good to have some liquid at 18 and some at 6, to bracket things. This is just typical/average -- people vary. Also, it is common to want one level higher for "craving" points, like first thing in the morning, and to switch down a level for chain-
vaping.
An important note is to drink lots of water --
vaping dries you out.
Good luck!