Cremina's are extremely forgiving. Get your grind set, flush slowly a few ounces to warm up the group, pull you shot. I move the lever at the top to get some of the air out, not the fellini move but firms up the lever. Then I pull the shot. Nothing fancy, 16.5 -18.5 grams depending which roaster I am using.
Lots of threads here on the cremina, orphan espresso has all the how to's by Doug, there are some temp studies out there as well, depending how much you think you need to control it. It does just fine bone stock, though I like to watch the bottomless portafilter.
Congratulations on the Cremina!
Just read again, first machine, wow, right choice
will not need another!