I use 100 mg base without breaking it down... it works well mathematically for manual mixing as well as for working in the juice calculators.
Since I like to vape 12mg juice...and I make 5ml test batches, I use .6 ml of nice base. To make 3ml at 12mg you would use .36ml of nice base.
I'm just starting also...check for a thread for whatever flavors you have (TFA, FA, LorAnnes) to get an idea of what % to start at. If nothing is listed, start small (5%) and you can increase from there. Also, take a hearty sniff of the flavor and if really strong try even less than 5% to start. You can always add more. (Tobacco and coffee flavors are typically really strong).
Also, when you see a post from Hoosier, read his blogs! Valuable knowledge is imparted within. You will end up with vapable juice if you follow these guidelines.
Lastly, if you have any issues, just post...these folks have been really helpful to me!
Thanks
Geo