We've recommended on many an occasion that you invest in a pedometer to track your daily steps. Heck, we just made the suggestion yesterday when considering how biking can blast belly fat. But Real Simple magazine (March 2009) warns that you should not purchase a pedometer until you consider that not all of them are as good as they're cracked up to be. Here, some guiding principles:

• If you fished it out of your kid's cereal box, don't count on it.
• If it uses a flimsy mechanism called a hairspring and costs less than $15, you'll be lucky to get six months out of it.
• If it's driven electronically or via a coiled spring and costs more like $25, it's more reliable.
• Measurements of distance, speed and calories burned tend to be inaccurate, no matter how much a pedometer costs. Skip these features, which are found on the most expensive models.

We still like the pedometer for tracking steps -- you want to score at least 10,000 per day -- and so we think getting one is a good idea. We also like these Real Simple tips, so we suggest you keep them in mind when making your next pedometer purchase.