You've started to bank some airline miles, and it's opening up some exciting redemption options--magazines, flights, hotel stays, airline VIP lounges--you can even use them to get a lawn mower! With choices come decisions: how should you spend your miles?
Figure out the value of each mile, using the price you'd actually pay for an item, not the item's stated value. Redeem miles only for items that are a comparatively good deal.
Redeem miles for something you would otherwise have to purchase.
Focus on earning flights, hotel vouchers, magazine or newspaper subscriptions or flight discounts and upgrades. Merchandise usually represents the worst mileage value.
Don't spend more on a ticket just to get miles with your preferred program.
Watch the expiration dates on your miles; program rules change often.
Purchasing extra miles is a notoriously bad deal. Do so only if necessary and if you need very few miles. Note that it can take a while for purchased miles to show up in your account.
Be careful when using mileage swap programs: the transaction is not skewed in your favor, which devalues your miles.
If there's nothing good available now, just wait: program offerings change.