These are expensive machines, so you’ll want to make sure that you maintain them properly. Always look at the manufacturer’s instructions first, because different machines will have different requirements. More generally, you’ll want to take apart your machine and clean the filter with warm water every day, or every time you’ve finished using it. You’ll also want to clean the steam nozzles by running them through, so that you don’t build up lots of milk inside the wand. Some machines will have a special clean or descale setting that you can invoke when necessary.