This is pretty explanatory however some tips for this include,
Complete control points and activities around the world
keep and eye on projects easiest way for this press back to go on map then LB/RB
complete main missions
collect devices etc
complete bountys
resupply control points
Yes this is a grind an no massive easy way than just keep going it'll come if you struggle on missions then you can matchmake
anything else please comment i will update thanks
p.s feel free to send an invite to our clan - UNDEAD Crew
edit: xx Bracc xx Said do not use level 30 boost as this voids this cheevo and others