Stick with Furniture That Fits: Like any room in the house, furniture choice can make or break a room. We recommend sticking with furniture that makes sense for the size of the movie-watching nook you look to fill. Don't shove a huge L-sofa where a two-seater would make more sense (and vice versa).
If you're renting, go a little cheaper (ie: Not buying a $3k sofa at Room & Board) so you can sell it off with less net loss the next time you end up moving.
TV Position Matters: Make sure the TV is hung at eye-level (gauge it with more than one person other than yourself) and purchase a TV that isn't too large/small for the space. Use this distance from sofa guide to help determine the correct size for the space.
When it doubt, cut a piece of cardboard, draw the TV, and hang it where you imagine the TV would be. You'll be surprised how well this works to get a feel for how the TV will look when you actually get it up and running.