I use flashcards, one side has English, one side has Gregg.
I spend some time looking at the Gregg and making sure I can translate it, then spend some time looking at the English and writing the Gregg.  
If I miswrite the Gregg, I right the word or phrase over and over for at least one line, maybe two if I've really botched it. 
I keep three separate piles. 
Group 1: words I know i know.
Group 2: words I'm pretty good at, but might miss or mistroke occasionally (such as making the 'r' stroke too long.  
Group 3: words I totally don't know or constantly mistroke
I spend most of my time group 3, some on group 2, and just  make sure I review group 1.  
Does anyone else have any practice tips? It's always good to know what others are doing, get a good ideas from others.