Before you do anything, let your machine fully heat up. I usually turn mine on before getting ready in the morning. Heating the whole group head will result in a more consistent temperature throughout a shot. I only insert my portafilter for the last couple minutes of preheating, so it’s warmed without being hot. With a hand grinder, I find the time to weigh and grind the coffee works well.
The amount of coffee you need to appropriately fill your basket will depend on your specific machine and basket. For my setup, I start with 20 grams and adjust up or down by half a gram until my puck is at the right height. To find the height for your set up, you want the top of the puck to be just below the shower screen. Lock in your prepared portafilter and check for an indentation before pulling the shot.
Another factor to consider while preparing your coffee is how coarse or fine the grind is. While the exact setting can change between bags, or even over the lifespan of the beans, espresso will generally fall within a narrow range. If you don’t know where to start with your grind, look up the recommended ranges for your grinder and use a setting in the middle of that range. As a note, decaf needs to be ground finer. Over the course of your first bag adjust until you are happy with the output, then use that setting as a starting point for future bags. If you consistently need to adjust in a direction, move your starting point. I find that 1.2.0 on a 1zpresso J-Ultra is a good starting point for caffeinated coffees, and 1.1.5 is a good starting place for decaf.
The next step is to prepare your puck. I have issues with channeling, the worst of which seem to be a result of unlevel grounds. This solution is to use a distribution tool, of which I like a WDT needle tool. If you need a temporary fix, combing through the puck with a thin metal object works. You just need to be aware it will be: slower, messier, and less effective. Additionally, a dosing funnel significantly cuts down on the mess while you comb through the coffee. After I am satisfied with the distribution, I tap the basket on the counter to settle the ground and tamp. I generally do two tamps for consistency, but if there are uncompacted grounds I will do additional tamps.
This section applies to unmodified Gaggia Classic Pros. I only do one ‘hack’ when I’m pulling shots, and find that I can get consistently great tasting coffee. After prepping my puck but before locking it into the machine, I flow water through until the indicator light turns off. Then when the light comes on, I wait 10 seconds. Finally, I turn on the steam mode to increase the temperature for an additional 5 to 10 seconds before starting my shot. I find something around 5 seconds works well for a darker roast and 7 to 9 is a good range for lighter roasts. The first two steps are to get a consistent base temp, and the third step is to get to a desired temperature for a given coffee.
When pulling shots, I rely on an espresso scale for quantitative data points which I later use to improve the coffee. I generally aim for a 1:2 ratio, although I have been letting my light roast shots go longer recently. I find 25 seconds to be a good target time for caffeinated coffee, or around 20 for decaf. If you want the best coffee possible, you should be tasting your espresso, as it will provide the most feedback. The general rule is that if your espresso is too sour, then you should change the variables you can to increase extraction. Similarly, if your espresso is overly bitter and astringent, you should work to lower extraction. Once you are familiar with how a particular batch of beans pulls, you can look at the time and extraction stream as a measure of the shot’s performance.
For a latte, I fill my pitcher just below where the spout begins with whole milk that just came out of the refrigerator. I set my pitcher at a slight angle using the spout as a guide, with the steam nozzle right at the surface. Once the milk has been sufficiently aerated, I move the nozzle down to incorporate the air. I know the milk is up to temp when I really don’t want to be holding on to the pitcher anymore, at which point I use a wet rag to clean the tip and purge it into a waste cup. At this point I stir my espresso and pour it into the cup I will be using. Then I start pouring my milk high and slow to mix with the coffee. Nearing the top of the cup, I will pause before bring down my pitcher and start pouring a design.
After finishing my coffee, I always use some extra water to flush the machine, reducing the build up of grounds in the waterblock/shower screen. I also thoroughly clean my portafilter and basket, and spray air using the included hand pump to clean my grinder. This doesn’t take long and will make future maintenance easier and result in better coffee. Once a week I will take a bit more time to clean my machine with a proper detergent, 5 rounds of 10 seconds on 10 seconds off with a blind basket. And about once every other week, or whenever I get new beans, I will disassemble and fully clean my grinder.