Theres no real way to rank up fast unless if its double xp weekend, use 200% Xp boost. If its not go ham and play tactically. Aim in before shooting someone far away, that way your accuracy is better.

Im level 110

Best class for score is assault, Domination is best game-type for score unless you're very good at conquest large, use your prefferd assault rife/carbine, v40 minis/rgo impact, prefferd pistol also use medic bag and defibs, also instead of joining existing squads press start go to team options and leave squad and press y to creat your own then set squad objectives by pressing RB when aiming at flags. hope this helps

You should also try to go for medals and assault stars, those help me level up really quickly.

I would suggest using the Assault class and throwing down medic bags as well as revive people.

Play the objective too because that gets you a ton of points.