I cook with garlic almost every day plus supplement with Vit C.
This winter I started to take Zinc supplements (immune booster) but I lost the tablets (not sure how really!) so I need to get some more.
If I get a cold I take echinacea with garlic tablets, have manuka honey (just straight off a spoon), and drink lots of water.
If my nose is really stuffy I make a mix of salty water, pour bits in to my hand, tip my head sideways and snort it (you could use a netti pot, but I don't have one of those). I keep my head sideways for 30 seconds or so before holding my head forward and blowing my nose. Repeat on the other side. It depends on how stuffy my nose is as to how many times I do this over the course of a day but it breaks up all the mucus and I have a clear nose for a certain amount of time (anything from 1 hr to half a day, depending on how much congestion there is) and my nose is much clearer the next day. I can't take cold and flu tablets (allergic to them), so do the salt water trick so I'm not blowing my nose every 2 seconds all day.
This works really well for me and I rarely get colds (a mild one every 18 months or so).