After you have done a few quests and earned a little bit of cash you can do this very easily. You will need $750. Head to the nearest BAAA machine which is an atm looking thing that you can pick your quests and buy your masks from. There are many throughout the map. One is right at the start area. A few of the other easy to find ones are at the bank where the Payday guys are robbing it, on the road by the pirate ship, and in front of the police station. There are several more but these are the ones I found myself nearest most often.
You can earn money by doing the quests from this machine, gambling in the casino, or licking or headbutting the right npc. There was a lady in front of the police station that I head butted that dropped a load of cash so you can try that.
After you have earned your $750 go to the atm and choose the crew gear option. Just buy the first mask
for $25 and equip it
. Do this a total of 30 times and the achievement is yours. I bought and equipped the same mask over and over until it popped. Afterwards there is an option to take them all off if you like with the d-pad