The machine will heat up by the timer. Give it >30 minutes in case you just switched it on.
If the machine did not make an espresso the last 5-10 minutes, make a cool flush, i.e. make a short run without porta filter to remove overheated water (see this movie).
Grind the powder (either 7g for single or 14g for double)
into a warm and dry porta filter.
Tamper (i.e. pressing the powder down) with roughly 15kg weight. With less, you might get "channeling", i.e. water flowing by the coffee powder. Try to keep tampering consistent. Single shots are harder to make than double shots, so team up!
Single espresso is 25ml, double 50ml - both set by the espresso machine. Or use the "K" bottom to make variable volumes (stop before the output becomes white-ish).
Brewing time should be 25-27 seconds. Adjust the fineness of the coffee powder to reproduce this time.
Afterwards do a wiggle-rinse. When not preparing another espresso, clean the porta filter, at best by loosely flushing water through the porta filter with a "wiggle-rinse": loosely lock the portafilter and run the pump while slowly jiggling the portafilter handle back and forth. This will wash most of the loose grinds off the grouphead and dispersion screen and over the sides of the portafilter into the drip tray. Be careful not to splash yourself and watch for hot water running down the portafilter handle (use some cloth to protect)! Remove water from the portafilter.
Remember to keep porta filter locked at the machine to keep it warm (put the other on top).
Cleaning the Machine
Daily: Do a wiggle-clean with the black porta filter with closed bottom. Do a backflush with clean water, i.e. use the black porta filter with closed bottom and let the machine pump for 5 seconds against it.
Every other week: Backflush with coffee detergent (white powder). This will breakdown the coffee oils and residue inside the grouphead, ensuring a clean surface. Fill 1/2 teaspoon of espresso cleaner in the black, blind portafilter. Add some hot water and let the cleaner dissolve. Backflush several times. The cleaner will change its color from initially white to brown to clean. If you do not reach the clean state, redo the cleaning protocol. Then clean the normal porta filter by dissolving it in hot espresso cleaner. Scrub the oily parts clean.
Monthly: Check the water filtration system (should be less than 3500l, the display startet at +100l and runs backwards).
Yearly: Descale your espresso machine once a year. No matter how good your water filtration may be, you're still getting calcium in your boiler tank. While small amounts of calcium won't alter the flavor of your espresso too much, over time that small amount will grow into a large amount causing a very bitter flavor in your cup and eventually causing damage to your machine. To do so, fill a 5l bucket with descale solution (citric acid, about one large spoon of powder per 1 liter?) and let the machine heat to operating temperature. Turn it off and empty all water out of the water tap wand. Close the water-tap connected to the Brita water filter. Open the tap of the loose water pipe (no water is supposed to come out) and put it in the bucket of descaling solution. Turn the machine back on. It should pump the water of the bucket into the boiler and stop once the boiler is full. Let the solution soak in for two hours – in the meantime run about half a liter of solution out of the wand and the brewing group twice to also descale those. Once this is done, close the descale-tap and open the water-tap again. Let ~3 boilers of clean water run through the machine to make sure all the descaling solution is washed out. Finally: enjoy the new refreshed taste!