Plumbers get more calls to unclog drains than anything else. Be careful what you put down the drain. Prevention is definitely better than cure.
Kitchen sink blockages are frequently caused by fats, emulsified by warm dishwater, being carried along the pipes and then cooling and solidifying, leaving a film of grease on the inside of the pipe. If this happens time after time, the grease builds up into a thick layer. Add a few coffee grounds, bits of food and other gunk into the mix and soon nothing will get through. It will start smelling bad too.
Take a little extra time to pour any excess fat into a can and dispose of it in the garbage. If you use a food disposal unit, always run the cold water long enough to make sure that the food particles reach the main line and don’t get stuck in the smaller waste lines.
Regularly remove the strainer or grate that covers the drain and give it a good clean. You may need a stick or spoon to dig out the dirt and grease. Clean the strainer in hot water to open all the holes and pour a couple of buckets of hot water down the drain after cleaning.
Hair is the biggest culprit with shower drains. Try and prevent it from going down the drain in the first place. Clean the strainer regularly, and pull out what hair you can. Oh what a fun job! At the slightest hint of a blockage, get your trusty plumbing snake out and try clearing the drain yourself to prevent it from getting any worse.