Here is all of my custom classes, use the one you like, I recommend the Stealth class.
Stealth:
Primary wep: SCARAB (use the Feline untill you get it).
Attachments: Reflex sight, Supressor and Extended mags.
Secondary wep: M12 NOVA.
Attachments: Supressor, the other attachments are kinda useless for this gun.
Explosive: The JAW.
Modules:
Armor: Energy Transfer
Stealth: Stealth Enhance
Power: Mobility Enhance
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Sniper:
Primary wep: The Gauss Rifle (use the DSG 1 till you get it)
Attachments: Pick whatever you like.
Secondary: M12 NOVA
Attachments: Supressor.
Explosive: The JAW
Modules:
Armor: Proximity Alarm.
Stealth: Blind Spot.
Power: Retriever.
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Close Quarters Combat (CQC)
Primary wep: Marshall (it's a shotgun, and use the Jackal till you get it)
Attachments: Reflex sight, Extended mags.
Secondary wep: Majestic
Attachments: Theres just one, the laser sight.
Explosive: The JAW
Modules:
Armor: Proximity Alarm.
Stealth: Tracker.
Power: Mobility Enhance.
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Heavy:
Primary wep: MK Mod.60.
Attachments: Reflex sight.
Secondary wep: Majestic.
Attachments: ...
Explosive: JAW
Modules:
Armor: Armor Enchance.
Stealth: Jammer.
Power: Rapid Fire.
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Assault:
Primary wep: SCAR.
Attachments: Reflex sight, Extended mags.
Secondary wep: Majestic.
Attachments: ...
Explosive: JAW...
Modules:
Armor: Proximity Alarm.
Stealth: Cloak Tracker.
Power: Weapon Pro.
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Now a few quick tips:
When playing on the Capture the Relay mode, use C4 instead of the JAW, put it near your relay.
Don't try to Stealth Kill (you now, melee an enemy by the back, using the Cloak mode.) an enemy that is sprinting, he will probably escape anyway and your energy will run out, leaving you vulnerable.
Manage your energy well, don't run completely out of energy because it will take longer to regenerate.
Heres 2 videos that might help you a bit:
http://www.youtube.com/watch?v=69gB0pR9F78
and
http://www.youtube.com/watch?v=oi2O0lqvp-c
Feel free to PM me if you need help with anything.
Cheers.