This is my first "espresso" machine so for me there's been a learning curve. Grind, tamp, temp, timing, start dump, blonding, etc. After learning and practicing and watching the stream for a bit I feel I can get consistently great shots from this machine, crema and everything. I vastly prefer it to my moka pot or french press (or automatic drip that I use for parties). I even prefer it to my local coffee shop.
Oh and I don't yet own a grinder that can get fine enough for espresso so I'm stuck using preground coffee in a can. Some brands are just too coarse or too fine to work. I find I can use Illy, Lavazza, or Cafe Bustelo to good effect. I start dump to compensate for not being able to dial in the grind.
Preheating is very important. When I get lazy and don't preheat I get sour results. Here's how I preheat. Take the basket out of the portafilter. Put portafilter in pot. Fill pot to submerge as much of the metal as you can without submerging the plastic. (Can you submerge the pastic? I dunno. I don't want to melt anything.) Start heating water. Meanwhile, fill and tamp basket. When water is almost ready, put out the portafilter and pop the basket back in and load it in the machine. By then the water should be ready so pour and pull.
As for pressure, fill the reservoir almost to the top and just stop pulling when the shot starts blonding. The extra water in the machine will allow for better pressure. Also, it's fine to re-pump if the flow stars slowing.
As for tamping, Illy sells a 50mm tamper for a very reasonable price. I've been using it to great effect.
I'm either gonna get a grinder for my upcoming birthday or I'll buy it myself shortly after. Then things'll get real! I think the skills I've learned on how to compensate for a less than optimal grind will serve me well moving forward.
And once I'm able to grind correctly then I can get into roasting! Woo!!!