I haven't done a craft fair in years, but things to consider.
Have pricing figured out for multiple purchases. If you have lap quilts for sale at $80 each (just grabbed a number out of my head) then if they buy two, make it $75 each.
Dress up your tables. Have nice tablecloths, and skirt the tables so that you can store boxes, etc. under them. Use an artificial Christmas tree to display ornaments or small items. Get lattice at the Home Depot to make a display "wall" for your booth.
MOST IMPORTANT!! Chat, laugh and HAVE FUN!! Craft fairs can be a blast!! :)