Honestly, I've completely given up not getting sick. We wash our hands of course, try to get enough sleep, and take Emergen-C at the first sign of a cold, but otherwise, I don't really do anything to avoid sick people. My son goes to preschool, so it's hopeless anyway. We'd never have a play date and I'd never get to see friends if we avoided each other when our kids were sick. However, I really feel like this year has gone much better than previous years when I've tried to stay away from anyone looking even remotely unwell. We've been sick with colds maybe 2 or 3 times this season and we got a stomach bug back in October, but really everything has been pretty mild and short-lived. My new philosophy is to catch everything in the hope that we'll all develop some form of super-immunity. Maybe not the best idea, but so far it hasn't backfired.
The hot foot bath idea is really interesting and definitely worth trying. I'll throw in the neti pot as well, which is my new best friend when my nose has issues, since I'm pregnant and don't want to take anything.