I use zinc lozenges or zinc gel in my nose. (The gel was taken off the market, but I never had any problem with it and stocked up. You may still be able to find it.) I find the zinc shortens a cold and sometimes even prevents it from happening altogether if you get to it soon enough.
Also, saline nasal mist is really helpful.
LOTS of fluids, and you can fill a sink or bowl or container with hot water and put a few drops of rosemary oil in it. It loosens secretions, and helps unstuff things.
I know, I can't take cold meds with my meds for pain and OCD. I can take small amounts of Sudafed, but it makes me feel like crap, so I rarely ever take it, even when I'm miserable. I usually let a cold ride itself out with REST, fluid and a few home remedies.
For me, Vit C gives me diarrhea (pretty, right?) so I have to stay away from it.