The most important thing that you need to do is to get the proper education. Most major networks will not even look at you for possible employment unless you have at least a bachelor's degree. The best course of action is to get enrolled in a college or university with a major in journalism, broadcasting, or communications.
Your classroom experience is not the only thing that you should worry about while you are in school. You will also want to gain some real world experience with an internship. Working as an intern can prepare you for TV careers in a way that you did not think was possible. Here you will be able to learn by doing, and you will make valuable real world contacts that might be able to lead you to TV employment. If possible try to work with a major network or news station, but even a local channel is better than no internship at all.
Next you want to get your foot in the door. Looking for hosting opportunities will give you some opportunities to prepare for your eventual TV employment. Check out your local stations, nightclubs, or even a cable access station. Again, this real world experience will help you to enhance your skills in managing a crowd and your general charisma. These things are essential for any major network TV employment.
Now you are ready to start marketing yourself. The way that you present yourself is essential to achieving TV careers. Your image is all that you have, and most hosting positions are looking for a particular package. Take a good look at yourself as a product for TV employment so that you can adequately market yourself. For example, if you have no interest or skills in sports then you should not try to market yourself as a sports show host. Instead, if you live, eat, and breathe fashion you may want to look at gearing your efforts towards a fashion based network.
When in doubt do not be afraid to take entry level TV employment. You may have to get in on the ground floor, but that clerks job may open the door for you to work your way up to an on air position. The truth is that if people start to work with you, enjoy the experience, and see you potential great things may follow.