I used to get ear problems quite a bit when i started flying, now i have learned to judge how bad it is.
If its present before work (ie: you cant unblock your ears with the Valsave technique whilst on the ground) NEVER fly, take an URTI.
Never fly with a cold/Flu/Sinus or any other kind of affliction that has anything to do with your ENT as it will cause congestion and blocked tubes too.
If for some reason you are fine on the ground but only notice it on descent continue every two minutes to unblock your ears (once they remain blocked for more than three or four minutes you risk reaching the point of no return where they stay blocked and nothing you do will help)
Anything that dries up your nasal/sinus passages will also help as it will keep your ear passages open a little wider than normal.
(ie cold and flu tabs, nasal spray etc)
As the public dont fly daily, to them its just somehting that happens 'sometimes' but to us you begin to realise that its the start of something more serious and when you fly daily it becomes a bit of a problem.
Some people find swallowing continuously helps (hence the sucking on sweets) but if it gets bad, Yawning is much more effective. With practice you can even learn to open your ears up the same way as you would if you yawned, but without opening your mouth.
Never fly with blocked ears though, you risk PERMANENT damage.