As much fluid as you can drink ( the immune system requires a high level of 'liquid' to function effectively not to mention that fevers can dehydrate).
Lots of external moisture - long baths, vaporizers, the old bowl of steaming water and towel routine.
Mind this: if it has followed a viral infection such as the 'flu or goes on longer than 10 days, see a doctor as it may be a sinus infection and those are right nasty and best to jump on as soon as possible.
For other relief, I use a hot flannel on the side of the face effected and also, do all those things that make me happy!

. So, lots of fluids, cheap novels and lolling about ( or whatever suits you) and don't let it go on to long.
Marto