MMU = Mineral makeup
MSF = Mineralized skinfinish
E / S = Eyeshadow
L / G = Lip Gloss
LOTD = Look of the day
TM = Tinted moisturizer
ELF = Eyes, lips, face (from there the website elf got its name)
BOGO = Buy one get one (take two pay for one)
There are about a thousand more abbreviations, and some that are completely unnecessary e.g. P / M = Pigment. Why do you have to shorten it ?!
By the way, did you know that MUA does not always stand for make up artist? Many just write MA because MUA is the abbreviation for the website MakeUpAlley which seems to be a very big makeup site in the US.
And I, and probably most of my blog readers too, am MUGs - Makeup geeks!