Writing an article is a very good way to earn acorns. I usually look for a topic that I know well and see questions about it from other members. Like how to grow a particular plant, or how to divide, prune, or transplant a plant. Or ways to save money on gardening. I am a budget gardener, so I've posted several articles on how to do something related to gardening on the cheap! Write about a topic that you know and have experience with.
Though, keep in mind that not all articles are approved. If not, try again with a different article. I typically ask if an article is worth writing about before I put my time into writing it. Sometimes there has already been an article published about a topic I was going to submit.