The most important thing in providing water is to be sure to keep it clean and change out the water daily. You do not have to spend a lot of money to have a water source. The saucers for potted plants with a few rocks work very well. There are small patio fountains to buy or make from a kit. If you have the space you may want to have a pond.
Shallow containers are better than ones with steep sides.
To attract birds the water needs to be no more than 2-3 inches deep. Please be sure to clean your water containers. Bleach or sudsy water are fine to use but take special care to rinse well. In the winter you will need to replace frozen water with fresh water. In conclusion, turning your yard or patio into a backyard habitat is a rewarding experience.