[edit] Steps

Verify that you have moles. Moles leave tunnels in the ground and are marked by lines of slightly raised earth.
Once it's verified, you have to stop and think, why would I have moles? It's probably due to you having an ample food source for them, hence, their calling your yard the buffet line.
Moles typically dine on bugs, so elminating their food source will send them looking else where. A good start would be staring and keeping a regular routine of applying lawn pesticide to minimize grubs and such. Take a look at the link included below, it gives a really good breakdown on all types of moles.

[edit] Tips

Finally, a trap that really-really works! It's called the "Easy-Set Mole Eliminator". After years of trying the various store bought remedies and other traps that only wish they were effective, this trap will eliminate the moles promptly. You will stand a little bit taller and your lawn will no longer look like a war-zone. You will be impressed with the results. Oils, poisons, gum, hammers, other traps....forgetaboutit. It may not be the cheapest ($34) but it is the most effective.
Easiest (and cheapest) way to rid your yard of moles is with Juicy Fruit gum. (must be Juicy Fruit) They love the smell and will come to it. Expose the hole, slide in one stick unwrapped gum (use rubber gloves so they don't smell humans) and replace the dirt. Do ALL the holes in your yard. You will quit seeing new hills immeadiately! When you do see a mole hill, repeat gum treatment. Smile - they're all GONE!
If you have a cat, pour some of your used kitty litter in the holes. Moles hate cats!
Red pepper or chili powder will help to move them out of an area as well.
When trying to trap a mole, remember that they can feel the vibration of your steps. They will stop moving when they sense something near.