I make a solution of salt water (plus baking soda is what my ENT recommends. At the first inkling of cold or flu, I use the squeze bottle and then the SinuCleanse (ENT recommended) upon waking and then every two hours. I also gargle with salt water after these. Ground ginger with a teaspoon of honey as required.
Steam is the only way to "get at" the lungs and the above posts are excellent regarding steam. Especially 9's safety tip.