Looking online, reading local wedding magazines and hiring a local wedding planner are all things I recommend doing in order to help you find the perfect venue. However, I do not recommend signing a contract with any venue until you get a chance to see it in person. You don't want to fall in love with a site based on images from their Web site and then get there and find out the place you already gave a deposit to isn't exactly how it looked in the pictures.
Take the time to visit the city you are getting married in, scout a few locations and meet with several vendors while you're there. You can even make the trip a mini-moon. Throw in some romantic meals and relaxation time and enjoy some time away.