I fly 100,000+ miles each year. My ears used to be a huge problem. Now I don't have issues as often, but when I do... here is what I try (in order):
1) Gum (rarely works); drink hot water (as hot as I can without burning my mouth)
2) Force myself to yawn
3) Swallowing with my mouth open. The key is that the jaw is in the open position.
4) Look "away" from the clogged ear (look left if it's the right ear, vice versa), and massage the area behind my ear as I yawn.
5) Hold my nose, and swallow.
6) Benzedrex -- nasal inhaler. USE SPARINGLY -- read all directions. Afrin if I can't find Benzedrex.
7) Hold my nose, close my mouth and "exhale" (Valsalva -- doesn't usually work for me either)
I will also sometimes take Advil and Sudafed before and during a flight if I am really concerned.
I tried Earplanes, but they actually made me vomit on ascent... So, while a great idea, they are not for everyone! I have a friend who uses noise-cancelling over-ear headphones. She says they help "just enough" to slow the pressure differential.
Lastly, if you are really sensitive, you may need to be careful with what airplanes you fly. Personally, I'm more prone to ear problems on Airbus planes. The really long or short flights (7+ hours or less than 1 hour) rarely give me problems.