Before, I used to just rip out what I wanted and throw the rest. However, I found I still wasn't making many quilts from magazines. So, now, I keep my mags for about 2 years and then sell, trade or gift, sometimes keeping one or two mags from each year. Right now, I'm making 2 kitty cat wallhangings and an HST quilt from magazines. Once done with the tops, both magazines will be sold, traded or gifted. I just keep too much stuff and really need to downsize to stop feeling overwhelmed by my hobbies.
Honestly, with the cost of the newsstand prices, subscriptions are so much cheaper and give you plenty of reading material.