Doppler anyone?

So, I bit the bullet and ordered a Fetal Doppler. I've been fighting the urge to get one since I found out I was pregnant. But I just can't take it any longer. Now, let's just hope that I can find the heartbeat. Any tips from those of you who have used one? It should be delivered tomorrow(Yes, I paid an insane amount of money to have it delivered overnight, on a Saturday).