It is important to add salt and rinse aid especially if you live in an area with hard water. Most dishwashers have an alert to let you know when these need to be topped up and doing this will ensure a better clean.
When adding salt to your dishwasher, use the funnel provided to minimise spills. Salt left on the inside of your dishwasher will overtime begin to corrode the metal.
If your dishwasher gets a lot of use, it is worth using a dishwasher cleaner once a month. Run an empty dishwasher on a cycle with the detergent inside to reduce bacteria in the machine and keep it smelling fresh.
Ensure you clean out the filter inside the machine regularly. It is usually located on the bottom of your dishwasher and catches dirt, grease, food residue and pet hair. If the filter is clean you will have far better results.