Remember, go up 2-4 inches from your pants size when buying a kilt. So, if you wear a size 32 pants, get a size 36 kilt. Their waist measurements are actually your waist measurement.
Also, the patterns have specific meanings. No one in the US is going to care, but if you go to Scotland someone may address you by the last name the pattern represents (they’re like family crests). There are generic patterns out there, though.