This is getting progressively harder and harder to do when you have competent opponents - on 0 starting credit maps, SMART players should set up a defense of two formidable inf. units as soon as THEIR credits hit 350. God knows anything I'M planning stops when I'm on GDI when my credits hit 800.That's the thing - ANNOUNCE these things. That way you get to scream when no one does anything.
350 - "WATCH OUT FOR ALLEY BUGGY RUSH"
450 - "SOMEONE GO UP AND CHECK OVERPASS FOR ARTY"
800 - "BUY MED. TANK - ENEMY SHOULD HAVE 800 CREDITS BY NOW"
I've found typing in caps helps a great deal, as it annoys people, but in that same vain, they at least look at it.