Don't stick vaseline up your nose. You can breathe it in and end up aspirating it into your lungs and cause lipid pneumonia.
There's something called Ponaris, I believe only by doctor's RX though. It's a natural oil that helps hydrate the nasal passages, and it doesn't have the agent in it that causes the lipid pneumonia.
Also, a cool air humidifier will do wonders. Don't use the steam ones, those will only end up making it worse long term.