Just gonna start this off with a couple of mine:
As a PFC, here is a cool gimmick:
Fake Spec:
If SADAR or SNIPER spec dies (permanently), take a shotgun into your armor with a mag-harness, m37 stock, angled, and BC as your attachments. Bait the enemy to attack you or even suicide rush into you (especially if you're wielding the SADAR).