I'll take a stab at it
OK, without talking about mods (modified or custom made e-citgs) basically the standard batteries are 3.7v. Different manufacturers offer batteries for each type of e-cig in a couple of maH ratings. The maH rating basically refers to how long the battery will last, at least in simplified terms. In other words, a 3.7v battery rated at 650maH will continue to power your e-cig for longer than a 3.7v battery rated at, say, 220maH before it has to be charged. How much longer is really a matter of the quality of the device, how you use it, and what atty's you use.
As for atty's, I've seen them from 3-4ohm down to 1.2ohm. Less ohms means less resistance, which means hotter vapor. Now, the trick is that the wrong combination can blow your atty's or drain your battery with a quickness. As a general rule, if you are using LR (low ohm) atty's (1.2-2.0ohms) you need a battery with a higher maH rating so that you aren't recharging your battery every 45 minutes. If you are using a battery set up that is greater than 4 volts, you probably shouldn't use LR atty's because they might burn out. They make HR(high ohm) atty's for systems running 5v or more.
Magic formula? Nope. It's a matter of needs and preferences. If I'm not mistaken, standard atty's are rated around 2.5ohm, and for many people produce enough vapor and throat hit to satisfy. That's what I use, and I was a heavy smoker of full flavored cigs for a long time. If you are looking for more vapor, then an LR atty will probably deliver that. If you want more throat hit, it might take a combination of LR atty and stronger juice, or just stronger juice. Battery upgrades will give you more consistent output for a longer period of time. So if you are a heavy vaper, then you might want a battery that is rated 650maH or more. 5v systems are usually mod systems, and will also produce more vapor because they let the atty get hotter. I use the E-go pass-thru, which is a 3.7v system that can also be found in 1000maH and can be charged while you are vaping via USB, which is so awesome it's dumb!
Different types of atty's will also affect vapor and TH, and so will different types of juice. I have heard that juice with a high VG (as opposed to PG) content tend to be milder. Some jiuce is 100% PG, some is 80% PG/20% VG, some is 50/50, and some is 100% VG. I use 80/20 I think? Some people say that cartomizers don't hit as strong as regular atomizers used with separate carts. I use a tank system, and I love it because there is nothing between the juice and the heating element - others use cartomizers and swear by them.
I'd start with an upgraded battery (650maH), regular impedance (ohm) atty, and find a juice strength and flavor that gives me a satisfying vape (menthol varieties work best for me as far as throat hit go - and I hear that cinnamons are wicked too). Just my

Hope that helps. I know that was more than you asked for...Oh, and welcome!