Walking backwards is pretty good if it works, i recall a moment on field when it was 20vs20 i got given a GDI Engineer, so planned my approach on teamspeak with few other guys, walk in backwards and once i got closer to gdi's base, mrls were shooting everywhere so i started shooting towards my own team so they didn't suspect me, casually strolled behind the wf, nuked... few seconds later few gdi come beside me and just run past me as i pretending i was defusing the nuke.. lol safe to say gdi lost wf right after that moment, and lost the game not to long after that..
Just gotta be clever in your approach