The most popular drain cleaners are very caustic. In these green times many prefer to use more safe, environmentally friendly and effective methods of drain maintenance. All you will need is a box of baking soda and a small (12oz.) bottle of vinegar.
It is important to only use a small amount of baking soda: about 2-3 tablespoons. If you have a drain catch that is difficult to remove then use a cotton swab to push the baking soda into the drain. Dry the drain area before beginning this process. You don't want the baking soda to get caked up around the drain. After you've put the baking soda in the drain, pour the vinegar into the drain about a 1/2 cup at a time. Immediately after you pour some vinegar into the drain, close the drain cover so the reaction is kept in the pipes and not in the tub or sink. As you pour you will hear the vinegar reacting with the soda, making a bubbling sound. Wait until the bubbling has stopped before you continue to pour more vinegar into the drain.
It sometimes takes a while for the bubbling to stop so I typically do this drain maintenence while I am cleaning the bathroom. I'll pour a little vinegar in the drain, continue cleaning and check it after a couple minutes.
Continue to periodically pour vinegar into the drain until you hear no more bubbling. If you run out of vinegar I recommend getting more and continue the process to ensure all the soda reacts with the vinegar. This is why you do not need much baking soda, if you use a lot it will take a great deal of vinegar to complete the process.
After all of the vinegar has been used to exhaust the baking soda run hot water through the drain for about 2-3 minutes.
This process is not meant to unclog drains but if it's used regularly (whenever you clean the bathroom) clogs will be much less frequent. And, as stated above, this is a very safe and environmentally friendly method of drain maintenance.