i see lots of great tips here, but i didn't bothered myself reading it all.
my tip: dont just go for a enemy flag, even if you are with a squad. take your time and decide when the best moment is. I see often people run towards a flag or try whatever it takes to retake a flag.
and squads, teamplay thats the name of the game here, its usefull to have someone with binoculars in your squad to spot for arti targets, this helps alot when attacking.