OK, this one's really simple cuz I have other things to discuss tonight.
when you pin 2 pieces of fabric together for sewing, aim the point of the pin toward the edge you are sewing. This way if you miss one and accidentally sew over a pin it will be the thinnest part of the pin and you have a better chance that the needle will slide over the pin, otherwise you will break your needle. Also, when you pin, you want the head of the pin (the ball) towards your left hand this will make it so that when you sit down to sew the pins will lay on top of the fabric in the machine and the fabric will lay flat. I usually pin about every 1-2 inches to keep things in place.