Hot water, washing up liquid and a bottle brush is the way most people do it.
But if you are referring to actual sterilisation rather than just cleaning it is a bit of a different matter. I myself plop mine in the dishwasher, but this is only safe for glass bottles and hard plastic ones. I've found the ordinary clear plastic ones melt even in the top rack. Some people in my cavy club use baby bottle sterilisers. You can also pour in alcohol, leave it to sit for a day, then rinse out with water, detergent and bottle brush.