Don't fry onions. That's one of the tactics suggested by real estate agents for making a house more sellable.

Cram the rooms with as much furniture and junk as you can. That'll make the rooms look small. Paint the rooms in ghastly colors. Put some old clothes or rags in a plastic garbage bag and wet them down. Then close up the bag until the clothes start to stink from mildew. Then open the bag just enough to let some of the mildew smell out. Keep the contents of the bag just wet enough to keep the mildew stink alive. (You might want to use an air filter while you're home alone so that you don't get sick from the mildew.) The smell of mildew will suggest the presence of hidden leaks in the roof or someplace like that.

See if you can get your neighbors to let someone you know who owns a motorcycle spend some time revving it up in your neighbor's driveway, making it look like you have noisy neighbors.

Good luck.