In addition to watching for blonding, I recommend you try the
rule of thirds to better discern the best stopping point. Returning to your original point...
bogrod wrote:I am not an expert so I don't really feel I have the reference point to say that I produce "o.k." or even "good" espresso (or crema for that matter).
You're working at a disadvantage with a pressurized portafilter (more
background info under
What is a pressurized portafilter?). Your original post didn't mention the grinder, but it's a critical part of the equation. Are there any good cafes nearby? If so, that should be your first stop with the goal of learning more about good espresso. As you can read in
Hall of Shame, for years I drank what today I would consider utter swill. It pays to know the difference, though be warned that you'll be forever disappointed by more of your cafe experiences.