The OP has already said he's confused, Keep it simple for him please. He wants to start mixing, then he should be encouraged to use a calc and follow it until confident with what he is doing. Than he can fiddle a bit as you suggest.
Hi Mono I am new to mixing but as I understand it, the higher the mg Nic base you buy, the less you will use thus making it more economical.If you want the TH, then as has been mentioned you will be better with PG nic base. You then need to dilute it with further PG and VG. Most of the flavours are PG based as already been said. I think most of the mixers, on the forum and also our dear Froggie from TAC use ejuice me up calculator Let us know how you get along with it
Get a good calc Read as much as you can in this section, there is a ton of info in here. Remember you will be dealing with a toxic poison, don't do it until you are happy you have all the answers you need.
Another good tip I learned here Mono was when you are starting out with mixing try and keep it simple using stand alone flavours so you only need to add 4 ingredients.
Nic base PG VG Flavour
Like most people said above download the juicemeup calculator and play about with it for a couple of days so you are confident using it, also when you start mixing write down how much of everthing you use then if you make one you like it is easier to make it the next time.
@mono - Sue and DJS are correct. Go with the 54mg since its the most readily available. This should work out cheaper and go further. You can get higher concentrations but 54 is most common.
Nic base ... this is your base which you will dilute down with PG/VG and flavour. Use the calculator to work out what the ratios are for your preferred mix. The target is made up of the base, the dilution (the VG addition) and will assume PG base flavourings. The flavourings will continue to "water" down the ratios of PG/VG. If using the breaktru calculator which has been mentioned, remember after making changes to click on the calculate button at the bottom to give you the final readings. It doesn't adjust until you do that.
Good luck! Look forward to some recipes dude !
EDIT ... remember that the top fields of breaktru you should set to the starting percentage of your base... if 54mg PG, set to 100%. The pg/vg fields beneath are your target