I know exactly how hard it is to learn to trust your own intuition. Over the years I've come up with an analogy: It's like talking on the telephone. You have no idea who I am, so if I were to call you on the phone I'd have to identify myself. But if your mother or your best friend were to call you'd know them just from the way they say hello.
Your intuition is just like that; it always speaks to you in the exact same voice (although that voice will be unique to you, describing how I know may not be useful to you) and the more you listen to, and learn to recognize, it's voice the easier it will be for you to identify it.
I'd have to say that I would never recommend learning to recognize your intuition by choosing relationships - especially not romantic ones. As other posters have mentioned all the emotional turmoil of lust, etc makes it really difficult to hear the voice of your intuition (which is really very quiet to begin with) especially if you don't already "know" the voice.
For deciding on the person I'd go with two general things. First, check your body's reaction. If there's a tightness in your stomach or a hesitancy then back away. Your body can always be trusted to tell you if someone isn't safe for you.
After that, I'd be willing to give them a chance; take things slow and allow some emotional space to be able to hear your intuition as the relationship develops. Remember, nothing's flawless. This may be the person for you, but they have their own will and can make their own choices and they may still hurt you because they aren't ready for the relationship. Anything that deals with other people so intimately is a difficult balance.
If you want to start learning to recognize the voice so that you can know it well enough to use with people, then that's easy. Every time you acknowledge your intuition your "inner ear" places a name to it and starts to be able to pick it's voice out from the many other inner voices. Start using your intuition for little things (which direction to turn, what dress to wear, who to talk to, etc..) and eventually you'll know the voice well enough to apply it to anything.