Step two

Vacuum all loose debris lying on the pool floor, including leaves, bugs, pine needles, etc. If debris is left to sit over the winter, it may lead to staining or discolouration, which can be difficult to remove in the spring. This is also a good time to clean the tile line to remove any buildup of scum and scale. Minerals and oils are also easier to remove at this stage and will leave the tile clean, so only a light brushing is required in the spring.
Step three
After vacuuming the pool, but before draining the plumbing, it makes good housekeeping sense to clean the filter. A season-long buildup of oils, grease and minerals will have likely left the filter quite dirty. You can leave it until the spring, but cleaning it now means avoiding possible damage to the filter media and less work down the road. If left to sit over the winter, problems such as caking (sand hardening) in sand filters or buildup on cartridge media can occur.
When cleaning the filter, it is best to use a cleaner made specifically for pool filters. Muriatic acid can help remove mineral buildup, but it is not sufficient at removing oils and grease. A good filter-cleaning product should contain surfactants for stripping oily waste and acids for removing minerals in a single step.
While sand filters are particularly prone to caking and clogging with contaminants, cartridge and diatomaceous earth (DE) filters also benefit from waste removal. Allowing oily wastes to sit over the winter allows them to deeply set into the filter media only to cause grief in the spring. Clean the filter now and you will be thankful you are not facing a more difficult task later.
Step four
After the swimming pool and filter is cleaned, disconnect and drain all water from the plumbing and equipment. Remove and store pool parts, such as skimmer baskets, ladders, wall fittings, etc. This process will vary by pool type, based on professional advice. At this point, it is also a good time to inspect all equipment for signs of damage or wear and repair/replace any worn-out items. Your customers will thank you for taking care of these things.