My favorite technique is what I’ve dubbed the modified tap nutation. It combines two simple techniques to get a quick easy and reliable distribution. I expect that it will not work well with cheap grinders, but it works very well with grinders like the Vario, the Super Jolly, and the titan grinders.
The hardest part is distributing out of the grinder into the portafilter getting a fairly even distribution from the start. I find that the easiest way to do that is to move the portafilter around under the grinder to manipulate the fall into the basket or even better – remove the basket from the portafilter and spin it under the grinder slowly ensuring that you get a reasonably even distribution without a large mound in the center or one side.
Now if you have a relatively easy distribution and you are using a fairly good grinder that does not create dense clumps the rest is easy.
You simply firmly tap the basket on the counter once or twice to settle the grounds. You do not want an uneven tap that sends the grinds sloshing. Finally you do a process called nutation where you insert the tamper in the basket and roll it around the rim having it contact the coffee in one or two full circles like a coin that has been spinning and is about to settle onto the table.
Now tamp and go (and never tap the portafilter after tamping – this is a bad habit pro baristas pick up and then casual baristas imitate that should never be done, but that is the subject of another post).
The tap and nutation together take about 15 seconds or less so they are quick and neat and with a good grinder just as effective as any other technique I have found.
With an amazing grinder like the giant conicals, you can probably get away with a couple taps or a nutation and not both if you are careful with getting the coffee in the basket in the first place, but then again twenty seconds to ensure a great pull is not that much of an imposition at home and for that matter is even quick enough to use in a quick moving professional bar.
I am not sure this technique would work with a lower to medium end grinder because it will not break up clumps, but I fell in love with it after I upgraded to fairly high quality grinders so it might work after all. Let me know!