Purchase some baits. Baits are one of the safest and most effective ways to eliminate roaches. They work over an extended period of time and can either kill roaches directly (when roaches eat the bait) or indirectly (when roaches eat the poisoned feces or corpses of those that have already sampled the bait). 
You can purchase baits in the form of small containers filled with bait (bait stations) or dispensable gels. A variety of bait gels and baited traps are available from most hardware stores, drug stores, and supermarkets. Common brand names include Avert, Blue Diamond, Combat, and Max Force.
Make your own baits. You can make effective baits out of a variety of household ingredients. Try one of these bait recipes:
Mix small, equal portions of white flour, cocoa, oatmeal, boric acid, and Plaster of Paris.
Mix 2 teaspoons (10 ml) of citrus pulp, ¾ teaspoon (about 4 ml) of brown sugar, ½ teaspoon (2.5 ml) of corn meal, and ¼ teaspoon (1.25 ml) of boric acid.
Bait mixtures containing boric acid should be kept out of reach of children and pets.
Place bait stations in identified problem areas. Bait stations are most effective if set up in areas where cockroaches are known to gather, such as cabinets, the spaces behind and under appliances, and areas where food and moisture are readily available (such as bathrooms and kitchens).
Avoid leaving your bait stations out in the open. They are more likely to be effective (and less likely to be found by pets and children) if they are placed under or between appliances, in dark corners, and inside cabinets.
If you made your own bait, put it in a small container, like a shallow bowl or a plastic food storage container lid, and place it as you would a commercial bait station.
Use bait gels in small spaces. Bait gel is ideal for cracks and crevices where cockroaches like to hide, but where regular bait stations will not fit.
Change and replace your bait stations frequently. Since bait stations serve as food sources for roaches, they will become empty quickly in areas where roaches gather. Empty bait stations can serve as hiding places for cockroaches.
How quickly your bait stations become empty will depend on how many roaches you have. Commercial baits may include instructions to replace your baits every 3-6 months, or more frequently if roaches return before the recommended period ends.
If you make your own baits, inspect them every few weeks and replace them once the bait is depleted or cockroaches begin to reappear.
Make sure other food sources are not available. For baits to be effective, they must serve as the roaches’ primary food source. Clean up and put away food in areas where your traps are set up.