1) Buy 5 tubes of clear caulk. They mostly go for the kitchen so start there. Pull out the fridge and seal the baseboards and along the cabinets. Then do the same inside the cabinets and the rest of the floor. Don't forget about the oven.
2) They live in the walls. Someone else pointed out if you see 1 there are 3 more hiding. If you are in an apartment - your screwed. But if it's a house, go to Home Depot or Lowes and get "Home Defense" for 5-7 bucks. Spray the parameter of the house real good. Spray the windows and doors. Spray the Garage super good.
3) Ditch any boxes you have. They breed in cardboard boxes and that's a common way for them to enter homes.
4) Set lots of traps. I suggest 1 in each cabinet including the bathrooms.
5) Close your drains when your not using them. They come up from the sewer. Such a sweet thought.