In the game there are "profiles," which are basically skillsets that you can pick and choose moves from. It's just like the class system in the other games, except now you can invest points however you want and aren't limited to the class you chose.
There are seven profiles to choose from, with skill point requirements to unlock each of them. You won't be able to unlock this really early into the game since you'll need to level up a few times, but it is still very easy to get. I unlocked it within three hours of play time, for reference.
Anyway, here are the profiles and requirements:
Soldier [6 Points invested in Combat]
Engineer [6 Points invested in Technology]
Adept [6 Points invested in Biotics]
Sentinel [3 Points invested in Technology & Biotics]
Vanguard [3 Points invested in Combat & Biotics]
Infiltrator [3 Points invested in Technology & Combat]
Explorer [3 Points invested in Combat, Technology, & Biotics]
Once you have enough points invested to have three different profiles unlocked at Level 1, simply change your equipped profile three times. You will most likely unlock this achievement simply trying different playstyles.