Knit with a yarn you really like
You'll have more fun knitting if you enjoy working with the yarn you've chosen!
Make a copy
If you make a photocopy of the instructions and circle or highlight the numbers that apply to your size and gauge before you begin you will avoid accidentally following the wrong column of instructions. Many people have copiers included in their printers now. A luxury we didn't used to have!
Always check dyelots
Make sure all the balls or skeins will match when worked up. Many times handspun comes in custom, one-of-a-kind skeins, but I've chosen to also spin up a commercially dyed wool for those that need consistent colors. You know, for those odd times you decide you want your project a bit bigger or longer.
Keep a notebook or journal
This is one aspect of organization that I often neglect. I know I should write down gauges that I get with different yarns, but I think I'm too busy. Take the time to write your knitting projects down so you can easily refer back to them when it's time to knit or crochet that project or at the very least, work a gauge with that same yarn you just used. Who knows, they may love their item enough that they want another in a second color!