There's a great how-to video on the Runners World site, but essentially the way you wrap your shoelace in the last phase of shoe-tying is the most important. Crazy to think about, right? So, for example, I start tying by crossing the right lace over the left. I then make a loop with the right side first. So it follows that in the next step of shoe-tying, I need to make sure and wrap the lace around the front of the loop. Wrapping around the back would make the laces off-balance, causing them to twist and potentially loosen. Depending how you start your knot dictates which direction you'll need to wrap, so take a look at this helpful chart to determine your style.
I promise, you'll never think so much about tying your shoes ever again!