Dairy products can cause a fourfold increase. Avoid tobacco and alcohol. Both tobacco smoke and alcohol irritate your mucus membranes, promoting more mucus that can block your eustachian tubes. Keep your mask clear. Water up your nose can irritate your mucus membranes, which then produce more of the stuff that clogs.
Some divers also feel vertigo from the unusual pressure on their balance mechanism.
Pointing the affected ear toward the bottom may help, too. Ascend as slowly as your air supply allows, remembering that the last 30 feet will be most difficult. Otherwise, you will just have to endure the pain to reach the surface. The loss becomes noticeable only after a few hours. You may not be aware of the loss until you have a hearing test.