Google Maps provides excellent directions with a lot of hidden features. Not only can you get driving directions, you can get walking, public transport, and biking directions, too. This tutorial assumes you're using the desktop version of Google Maps. You can get directions from your mobile phone, but the interface is slightly different. The concepts are the same, so this tutorial may still be useful.
To get started, go to maps.google.com and click on Get Directions on the upper right hand corner.
You may also notice a link labeled Set your default location. This is an optional step to set the place you're most likely to need driving directions from. In most cases that's your house or your business. If you click on the link and set your default location, that saves you a step the next time you get driving directions. That's because Google will automatically add your default location to your starting location.