The only way to "lower your ping" is to play on a server geographically closer to you. Filter the servers by location, pick your continent and don't use the server latency reading in the server browser (it's usually WAY wrong). Anywhere on your continent should give a ping of <150 which is fairly playable.
The rest is all practice I guess. The really dumb thing about this game is that once a player has fully unlocked all attachments for a weapon and leveled modules to Tier 3, his gun is going to have WAY less recoil/spread and possibly even higher damage rate (Rapid Fire) than the exact same gun being used by a newbie, giving the newbie even less of a chance. It's really stupid in a competetive multiplayer game where everything should be fair n' equal, but the only way you can deal with it is pick a weapon and stick with it till it's nice and leveled.
Sooo currently the overpowered weapons are Scar Mod 2 and Alpha Jackal. There is nothing that comes even close to these two guns right now, the Jackal especially in close-midrange maps is almost unstoppable. Scar/Jackal are getting a bit nerfed in the upcoming patch but they should still be strong and usable. Level up those weapons, use module combinations like Auto Armor + Weapon Pro + Maneuverability, or Auto Armor + Rapid Fire + Maneuverability, etc. Stay constantly on the move, camp as less as possible and try to keep your back covered...movement plays a huge role in this game, helping you staying alive and gaining an edge on enemies.
Practice practice practice, beginnings are always very rough in fast-paced games like these