Just as bonsai has many components and there are multiple avenues to explore, your choices of subjects for articles is also very wide. Anything to do with bonsai.... from how-to's; to interviewing artists, growers, nursery operators, potters, woodworkers, club organizers, people who specialize in accent plants, suiseki, hon non bo, saikei, etc; to historical articles on aspects of bonsai like historical collecting, species domestication, the changes in bonsai design and thought, cultural influences; propagation such as cuttings, air layers, seeds, specific species propagation, the role of sports in developing new cultivars; bonsai fiction or book reviews; humorous essays; the role of sketching or photoshopping in visualizing bonsai futures; how to sketch, how to photoshop, how to visualize; aspects either specific or general about display, accent plants, scrolls, mudmen, choosing a table, showing the tree or display to its best advantage; collecting pins; the role of clubs in bonsai education, good projects for clubs, how to set up raffles, how to raise money for your club, how to bring good presenters and give them the advantage in what they bring to the club, setting up a club newsletter, setting up a club website; how to sew happi coats; judging bonsai, setting up a show, publicizing a show, displays for a show; species outlines; diseases, pests, fertilizers, (dare I say it?) soil, pot care, tool care.....
Those are just a few ideas for subjects, the range is wide and varied.
Good luck, and start thinking!
Joanie