With my Rancillio Silvia, I will give my machine a general clean after each use as good practice, and will then give it a through clean every month - you might want to extend that to bi monthly, quarterly or every 6 months, depending on your usage.
After each coffee making session, I will do what I call the 'portafilter shuffle', which is basically wiggling the portafilter with the group head water running through the group head. That will assist in removing any coffee grounds between the coffee group head and the group head seal. also cleaning the shower screen while giving the portafilter and basket a nice rinse. If I use the steam wand for milk, I will give the steam wand an extra blast (to clear out any milk inside the wand, then clean the wand with a cloth warmed from the steam (be careful). Other than wipe the machine down, that's pretty much all I do out of habit.
On a monthly cycle, I also give my machine a back flush by using a back flush blanking plate for the portafilter and back flushing powder. Use just a quarter teaspoon of powder, backflush according to the directions, repeat a few times and then follow up with a backflush series of just water to clean out the pipes from the backflushing solution. Empty the drip tray and your done. (I will generally give the group head seal a clean using a stiff group head seal brush, while the backflush solution is still in the system and then continue backflushing).