Get in the line that is moving the quickest. Border Crossing officers are all different and some are more strict than others. A quick line usually means a lenient officer.
Take off your hat and sunglasses. This helps the Border Crossing Officer to identify you easier when looking at your license. You want to make his or her job as easy as possible when its your turn to be evaluated.
Turn off the music. Loud music is disrespectful to the Border Crossing Officer and you want to prevent angering the officials in any way. Don't make him or her shout over your music.
Have all of your paperwork ready to go when you reach the booth. Don't make the Border Crossing Officer wait while you gather up your identification papers.
Answer all questions honestly. If you trip up on answers or appear to be lying, you'll be pulled over for sure. Go ahead and be honest and you are much more likely to be sent on your way.