"3. It's best to tell the person that you like them, unless they are already involved with someone, then just let things run their course."

I never thought I'd be seconding James Caan....

Honesty, is the best way to go, it will give you the most direct answer as well as avoid many possible miscommunications. If the person you have feelings for has a steady already, perhaps you should make like an aforementioned cow and make your way to greener fields. Otherwise, the other option is to wait and see. However, don't tell the person you have feelings for them in hopes of ending their current relationship. That's never a good idea.

Take care all.