I need help decorating a very odd shaped long but narrow living room???

My living room is almost two rooms. When you first walk in there is a tiled area (3ft x 3ft) to the left is the fireplace on the back wall, but off center to the front is the double window. there is a vent below the windows. half of one wall is the door to stairs to the basement and then it goes back about 10 feet to a wall with a closet on it. It's very odd.... I need help trying to figure how to decorate it fairly cheap. Less than 500. if possible. the best way i can think to describe it is like an outlined backwards L with doors and entry ways on all the walls!!!! I'm so confused. Please help!