Personal preference is key here but generally a narrower board (7.5") is going to be used for street skating/people with smaller feet whereas a wider board (8") is better for vert skating/people with larger feet. Smaller riders under 70 pounds should look for a "mini"model.
Compare the skater's height to this chart:
| Height | Under 4' | 4'-4'10" | 4'10"-5'3" | 5'3"-5'8 | 5'8"-6'1" | Over 6'1" |
| Board Size | 29" or Smaller | 29"-30" Long | 30.5"-31.5" Long | 31.5"-32" Long | 32"-32.5" Long | 32.4" and Up |