Kitchen sink clog are, more often than not, caused by food waste that is bound together by oil and grease. You can save yourself a lot of heartache by always scraping leftover food into the trash, using a drain screen, and never, ever pouring grease or cooking oils down the drain. Once the oil has cooled, pour most of it into a container you can recycle, then blot the remaining grease with a paper towel before washing the pan in the sink.
When it comes to the shower and bathroom sink, the number one culprit is hair that is bound together with soap scum. Believe it or not, traditional bar soaps are made from fats and oils (yuck). Installing a shower strainer and switching to liquid soaps will go a long way towards preventing clogs.
Lastly, don’t flush sanitary products, diapers, cotton balls, cotton swabs, or anything other than toilet paper down the toilet. Making sure you have a wastebasket in each bathroom will help you (and your guests) avoid the temptation of flushing things that can lead to clogs.