Summarize:

Before you get married, the ring should be worn on your right hand, rather than your left. Wearing it on your ring finger shows that you're romantically inclined, but have not yet found the person you are going to marry. The heart should point toward the end of your finger, rather than into the center of your hand, and the crown should point inward. This shows the world that you're open to finding love, and that your heart is available to give to another person. When you've found someone special and made a commitment to date them, turn the ring around so that the heart points toward the center of your hand. This shows that your heart is currently unavailable. Leave the ring on your right ring finger, though, since you are still unmarried.
Wear the ring on the ring finger of your right hand. Wear the ring with the heart facing out to show that you're single. Wear the ring with the heart facing in to show that you're dating.