Some subjects look better vertically, some horizontally. Look through your viewfinder to see which looks best. If in doubt, take it both ways and decide later which is better. Use slide film, not print. Although many newspapers and magazines will accept prints, most prefer slides because they are sharper, give better color, and reproduce better when published.
Most professional photographers take slides.
Marketing Do not send photographs with your queries or completed manuscripts, but do state the availability of photographs in your cover letter. Editors will request photos if they are interested in your article, but their availability will increase the chances of acceptance. I have occasionally violated the don t send pictures rule by sending inexpensive prints with my query on the assumption that seeing the photos will help make a sale. Sometimes it works. When you send slides, send duplicates because slides are often lost or damaged.