There's a reason I keep hand sanitizer on my desk and try not to touch anyone else's keyboard or answer their phones. I find that's the best way to avoid catching a cold.
I had a coworker who stayed sick all the time, and I've said on numerous occasions that the three times I've had bronchitis came about a week after I picked up her phone to answer it. Apparently, she was a modern Typhoid Mary.
After that, I'm very careful about touching anyone else's stuff. I use my hand sanitizer and hope for the best. So far, I've been pretty lucky.