Okay, first off, you don't have to try and do all of the math by yourself, there are calculators out there (like this:
E-Juice / E-Liquid Calculator), though, it doesn't hurt to check it yourself just to make sure.
You can start off with an 18mg base if you'd like. The thing to remember is, the more concentrated the nic base is, the more you'll get out of it. 36mg base will obviously last you twice as long as the 18mg. However, it's important to note that the higher in nic you get, the more dangerous it could be if it comes in contact with your skin, animals, children etc. I think I remember someone once saying, "I treat DIYing with nicotine like I treat a loaded gun." Great advice! Use gloves, and have a work place set up (I just place paper towels down on my desk here).
Okay, so, the abbreviations next to the flavorings are the company in which that flavor derives from. For example: TFA is The Flavor Apprentice (or The Perfume Apprentice, same thing). FA is FlavourArt, CA is Capellas, FW is FlavorWest, SM is Seedmans, and so on.
On your first purchase, try and purchase/have as many bottles as you do flavorings. That way, you can test each flavor individually before trying to mix (optional, of course). I would invest in a couple of syringes, at least one for each bottle it will be touching (For example: if you're using PG, VG, and a nic base, I would get at least 3 syringes with blunt tips). You can use syringes for flavorings as well, but, I just use 1ml pipettes. It's all up to you.
When you start mixing, start off at low %'s (General rule of thumb). You can always add more flavoring if it's weak, but you can't really remove it if it's too much.
Anyways, that's what I got so far. Good luck, and feel free to ask specifics.