Just make sure that the yarn is always on the needle in your left hand when you begin a new row. Then it will be on your right hand needle for the rest of the row. After you are finished with the row, turn the whole deal around until the yarn is on the needle in your left hand again, then begin the next row. I recommend that you finish a whole row if possible before putting it down for a while. It makes it a lot easier to remember where you were. Remember...yarn starts out on the left needle, finishes on the right.
My first attempts were frustrating, I would occasionally knit in a circle and I didn't know why, until someone taught me this.