I use several different ways:
group according to  : month of birthday e.g all January birthdays go together
                               : day of month of birthday eg, 1st, 2nd, 3rd
                               : colours they are wearing
                               : type of shoes
                               : favourite colour, music, band, etc
                               : different coloured worksheets so pink work together, green and so on
                               : hair colour, length of hair
                               : letter of the alphabet that their first name begins with, second name
                               : age of grandparents, siblings
                               : number of cousins
                               : mother �s birthday (month or day not year!), father �s birthday, siblings
There are a myriad of ways once you get into the swing of it.
Just be prepared for a few minutes chaos as they think about the answers and then forget their groups but it is worth it in the end as it is still reinforcing English.
Cheers Joy