If you are good at search and destroy that I. Think will give you he most sp other than that I recommend demolition.....that is what I play to rank up....you can either use a good gun with three attachments or what I like to do is .......get perk 1 as lightweight and take perk 1 greed and get blind eye......perk 2 as cold blooded........and perk 3 as extreme conditioning hen perk 3 greed as dexterity and you can still get some equipment or attachments for your primary weapon this is the strategy I use and it works for me.......hope I helped

The best way to level up is get a team and play hard point because that gives u the most xp and run uav counter uav and VSAT , if your not a fan the second best is kill confirmed and for guns use what ever is best for u and also don't just go for kill play the Objective

Gt: ELMO xx Fame