Purchase more walls and tiles to expand your restaurant. Space can run out fairly quickly and you will need to invest in more assets in order to expand. Save your money and expand outwards into the grassy areas with different equipment, such as tables, chairs, stoves, and other items. Keep searching for new areas which you can expand. If you do not have enough cooking stars to expand, look at your current appliances and search for the foods that can be starred the fastest. Cook them, serve them, then try expanding again later.