It is going to be your first trip to Dallas. The big question is where to stay. The Dallas-Fort Worth area is huge. It is often referred to as "The Metroplex." The first thing you should consider is the reason you are in Dallas. Is it for business, for a sporting event, a visit to family or the State Fair?
Next where are your meetings, downtown or somewhere else? Where is the sporting event, at the American Airlines Arena, Cowboy Stadium, the Cotton Bowl, Texas Motor Speedway or Arlington Stadium where the Rangers play? Where does your family live? Now how much driving do you want to do, or would you prefer to be able to walk or take public transportation? With those things in mind you can start looking for your hotel.
Find one near where you'll be spending most or your time makes the most sense. So once you decide that you can concentrate your search in that area.
The light rail system makes it easy to get to some places so you do not always need to stay nearby. For example the train now runs to the State Fair grounds. There are not a lot of hotels right near The Fairgrounds, but the rail runs from downtown out.
Now you've decided where to stay how should you book a room? If it's part of a chain, calling the 800 reservation line is often the easiest. But be aware those operators will have the least flexibility on price and exact rooms in the hotel. Calling the actual hotel can be a boon for you. The desk at the hotel can give you a discount if they know they'll have rooms. They can also help you get on an appropriate floor. And even if the hotel is sold out for a convention the desk might be able to help you anyway. They've always got a few rooms set aside.
Aggregators are another way to go. That's services like Orbitz, Priceline and the such. They can sometimes get you a decent deal but if it's a busy time at the hotel, such as when there is a big convention in town, like the one you're going to, they might not be able to help you out.
Speaking of discounts, do not be afraid to ask. Many hotels have deals for members of some auto clubs and other groups.