How can I best heat an 800 sq ft room with space heater(s) and save on electric bill?

My living area consists of one room which is the living room, dining room and kitchenI'd like to cut way down on my electric bill but cannot find any space heaters that will heat a room that sizeIf I use 2 or 3 space heaters, I may be defeating the purposeIn addition, I need a heater for my 10 x 15 bedroom tooLooking for suggestions.