There are three ways of mounting a TV - low profile, tilting, and full motion mounting. If you are looking for the cheapest way, then low profile or flat mounting is the best choice. With tilted mounting, you can move the TV to about 15 to 20 degrees. Lastly, if you have a relatively larger room and a well-spread seating arrangement, then you can opt for the most expensive way of mounting a flat screen TV. Here, you can install the TV in full motion or an articulated manner. This way, you can rotate and tilt the TV in the direction that you want.
On the Wall
Once you finalize the location, then the most important thing to consider is the height of the TV from the floor. You need to ensure complete comfort while choosing the correct height. The screen should be at a comfortable eye level. It may require you to consider the height of the seating arrangement in your room. Make sure the height that you are choosing is comfortable for you as well as your family members.
Above a Fireplace
Here, your biggest concern would be the fireplace temperature (and the smoke). Most television types can sustain 90 to 100 degree Fahrenheit, hence you need to check the temperature of the area above the fireplace where you desire to install it. This temperature may differ with different TV models, hence check the user manual before proceeding.
Considering these facts, there are only two options available for you. First is to mount it above the fireplace at such a location where the heat from fireplace can't reach. The second option is of installing it on a stand above the fireplace mantel. The mantel will surely protect the screen from smoke and temperature from the fireplace as well.
In a Corner
First of all, make sure the corner of the room that you are choosing is the focal point. In other words, make sure that the TV will be visible from most of the directions of the room. After you decide the location you need to find out the required corner wall mounts. Now, with the help of the provided manual, attach the mount to the back of the TV as well as corner of the wall.
If you are not comfortable with this DIY project, then the best thing to do is to call the home improvement professionals who are the best in the business!