Get a life. That doesn't mean that you should become "unavailable" to him for a short period of time, or play games by pretending to be busy when you're not, as some romance columnists advise. It means actually having a life and interests of your own. If you're busy doing things that you love, you're more likely to meet a man who'll love you for who you are.
Dress the way that you dress. Maybe that includes wearing sweats and no makeup to the grocery store, where the man of your dreams might be lurking in the produce aisle. If he's really the right one for you, he needs to know you're the one no matter what you're wearing, and to see you as beautiful when you're dressed to the nines or in desperate need of a shower.
Stop settling. Perhaps the reason no man has proclaimed his undying love for you is that you're trying to persuade the wrong sorts of guys that you're the one. Stop playing games and start focusing on matching your core values, and then you won't be working so hard to convince him that you're it.
Be yourself, but not always on your best behavior. Instead of trying to hoodwink a man and argue him into believing you're the one by only showing your best assets, let him see the real you. Let him learn that you like to lounge on the couch on Friday evenings, that your pet cat is your best friend or whatever other quirks you inevitably possess. If he still believes you're the one, then maybe he really is a keeper.