Run some extra water through the brew group after brewing and use a group brush to remove any remaining coffee or residue.
It is very important to keep the frothing wand clean because it comes into contact with milk. Wipe it down with a damp cloth after frothing and steaming and run extra steam out of the wand to eliminate any milk that may be inside.
Clean the filter basket and portafilter by hand using mild soap. Never put them in a dishwasher as the metal will corrode. Pay special attention to the filter baskets - the small holes can get clogged, not only blocking the flow of espresso, but also tainting its flavor.
Minerals in water build up in the machine and will eventually affect the taste. To remove the mineral deposits you can either buy espresso machine cleaner or simply brew one part distilled white vinegar with one part water. You will need to run water through the machine two or three times afterwards to clean out all the vinegar.
Put the decalcifying solution into a full reservoir of water and run it through the machine. With semi-automatic machines, you should also soak the shower screen, filter baskets, portafilter and steam wand to remove any deposits.
Decalcifying should be done every three to four months depending upon the frequency of use and the hardness of your water.
Never use soap or dishwasher detergent to clean the inside of the machine as it may lead to corrosion.