When you dig up a shovel full of dirt and you see worms that is good soil.
The worms make the soil haPPY.
To keep my worms haPPy I digs holes in the soil ad throw in egg shells, fruit and vegetable peeling and other greenery. It's makes them fat and happy and keeps them around to help my plants. Don't bury any kind of meats. Just vegetation.
do they like alot of moisture?
They do need moisture, but they prefer sort of "crumbly moist" not soggy.
Shelley E, also give them coffee grounds. Mix it in with the dirt. Your worms will smILE.
Kepp your worms happy and you'll have happy plants.
I have heard at least 10 worms per square foot is a good worm population. Soil should not be totally dry nor soggy and contain some organic matter. Many gardening chemicals and tilling are harmful to earthworms. Those are some of the reasons I tend my yard organically and don't till. You might be interested in this: http://www.instructables.com/id/Worm-Cafe-Compost-with-earthworms-right-in-your/
If you know anyone who brews beer, worms LOVE the spent grain after brewing is complete. Just mix into your soil, it will make your worm population multiple quickly.