Communication! Communication! Communication!
Truthfully, the only way to get a great haircut is to explain what you want carefully. Barbers/stylist aren't mind readers. If you are having trouble verbalizing what you want, search the internet and magazines for a look that you feel "best" suits you. Pick your top two or three, and show them to your barber and let him/her make the final decision.
Most barbers appreciate when their clients have a picture of what they would like. Also, make sure your barber or stylist listens and can confidently communicate back to you how they are going to achieve that look for you.
Without proper communications you could have another surprise coming!