Yes, there are a couple of things you can do to check and maintain your water heater.
First, shut off water to the heater and drain some water out of the bottom (there should be a drain plug that you can unscrew). Watch the water as it comes out. If it has sediment, keep draining until it is clear...slosh the tank a bit and drain again. Keep doing until the water runs clear. Next, remove the annode rod. Most WH's have a large bolt head on the top of the WH (usually requiring a 3/4" or so socket). Carefully unscrew this and even more carefully pull out the rod so as not to knock off any sediment. If the rod is only slightly pitted or corroded it should be ok. But I have seen them completely eaten away by minerals in the water. If it is badly pitted and corroded, replace it with a new rod from a plumbing supply house. Finally, remove your bottom heating element (if electric) and inspect it. If badly pitted/corroded, replace it and inspect the second element above it. These come out the side of the WH and are usually held in by machine screws.
There are some very good books in the library that can describe these procedures in more detail with nice pictures to boot :-)