Which modules exactly are u referring to about... if ur talking about all poewr and stealth module... i think its quite hard to list them all here... different modules have different tips to quickly upgrade... what are the ones u havent finished yet?
Generally those modules which u just have to have the module equipped and kill with it... its rather straightforward... just keep killing as fast as you can...for version 1.8, i think the best gun for this is SCAR... before this FELINE was great for killing sprees but i think its a bit weaker now. Also, create ur own waypoints in a map that will go past spawnpoints, and places where there will be some enemies.... while avoiding chokepoints with alot of gun fire and people fighting...
The rest which requires some additional things like being within a certain range of your enemy... that requires a different game play... if you need to be close to the player... then u gotta sit and listen out for footsteps.. and start cloak stalking ur enemy and kill at very close range...
For example Blind Spot module is abit hard... u have to wait for an enemy to use maximum radar... before u go on a killing spree... so listen out for those announcements saying that enemy radar is online.