The Grind
The grind texture is a very important aspect of shot quality: If it's too fine it will result s in a slow, over-extracted shot that can taste bitter and burnt. If it's too course it will be a fast, under-extracted shot with a weak and watery consistency and sour notes.
The Dose
The dose is the amount of coffee grounds that you put into the portafilter for your shot. The proper dose for a double shot should be between 14 - 18 grams, depending on your espresso machine and personal preference
The Tamp
The proper tamp method is to hold your elbow at 90 degrees, rest your portafilter on a level surface and then apply 30lbs of pressure until the coffee has an even and polished look.
The Pour
Place the portafilter into your machine's brew group and put your preheated cup under it. The volume of water for each shot should be 1 oz., so after your double 2 oz., stop the shot.
The brewing time you're looking for is between 20 - 30 seconds, so if you' re running too long or too short, check your grind, dose and tamp, then adjust it accordingly.
You want to create a fine golden crema atop a rich dark brew that tastes sweet and smooth. It's well worth the time to experiment and learn how to pull the perfect shot from your espresso machine the result will be excellent espresso drinks every time.