As Veebee has said, a nasal spray and aspirator. Calpol make a nasal spray that is suitable from birth, Isobel has got a cold this week and we've been using the spray and the aspirator. It does help clear the nose out a bit for a while, but she'll probably still be snuffly - same as when you're an adult with a cold, you blow your nose and a minute later you're all snotty again! It's still worth doing though. Be prepared for tears, Isobel screams blue murder when I go anywhere near her nose!
Putting her to sleep with her head raised will help her breathe. You can you this with a book under the legs of her crib/cot or if she sleeps on a thick cot mattress you can put a pillow under the mattress (not under the sheet as suffocation risk, must be under mattress). Also you can run a hot bath or shower to steam up the bathroom then take her in there for a bit to get steam vapours up her nose - obviously don't put her in the hot water and if she's got a temperature don't let her get too hot.
When she's older if she gets a cold you'll be able to use calpol paracemtol (2 months) and karvol decongestants which is a strong smelling oil you put on a tissue to inhale (3 months).
