Keep reprint rights to articles or stories.
Are you looking at places to sell your articles or personal experience stories? Pay close attention to listings in your Writer’s Market describing not only how much magazines pay per word, but what rights those publications expect to obtain from you. If you sell only first rights, you can retain reprint rights to resell your articles to other magazines or include in book compilations.
Need more detail? See: “How do magazines pay writers for articles and stories?”