Espresso Brew Guide
There are so many variables between machines and grinders that this could take an entire page, however, we recommend that you try starting with a 1:2 brew ratio, in 28-32 seconds of brewing time. In a cafe setting, this recipe was typically 18g coffee to 36g espresso.
For home machines, there are many different manufacturers and form factors. Your portafilter basket may have a size recommendation for maximum dose (eg 16g, 18g, etc.) That is a good starting point, but you can typically add slightly more coffee than the max.
Ultimately, brewing great espresso requires learning some technique and skills. A great educational resource is this video series by former world barista champion James Hoffman.