You'll get this achievement while working toward either; Solution for Power to the People in Transformers: Revenge of the Fallen
or Solution for Spoils of War in Transformers: Revenge of the Fallen
, the reason I've linked those solutions in is because they provide a full breakdown on how to obtain enough Energon to buy all the upgrades in the game!
That being said it doesn't matter which side you choose to play as for this achievement nor what you choose to upgrade first! This will just unlock the moment you upgrade something to it's first level.
Upon completing a level you'll be taken to a menu that allows you to press LT/RT to switch through the display, "Team Upgrades" is what it automatically starts up as, just choose an upgrade after your first mission and pump your Energon into it!