Buy some Earplanes. You wear them in your ears and they help your ears deal with the change in pressure. Also take some Benadryl or Sudafed before take off. Drink frequently, and/or chew gum or have a lollipop. Swallowing frequently helps with the pain. If your sinuses are very bad, you might want to try a nasal spray about 30 minutes before take-off. In general, nasal sprays are not good for long term use. Flying is the only time I use one.
I took all of the above precautions and had a GREAT flight going to MCO, but a painful landing on my return flight. My sinuses are bad and it's hit or miss on whether those precautions will work on me. I hope you have a good flight.