Summarize:

Treat tagging just like any other art form. Learn about its evolution over the years so you can spot the difference between modern, classic, and outdated trends. There are plenty of books and other materials on the subject, but popular titles include: Subway Art, written by Martha Cooper Style Wars, directed by Henry Chalfant Before you attempt your own tag, check out other people's styles. Photograph local artwork or save online images that impress you. Use these as reference as you start to develop your own style. Find these by: Searching online for uploaded images of tags. Taking a walking tour highlighting areas with active graffiti artists. Going on your own hunt for tags in your area. Keep in mind that a lot of graffiti is against the law, which means many artists have to work with only half their mind on the job at hand. Since the other half is distracted by having to keep an eye out for the cops, expect illegal tags to often be rushed and less than stellar. Because of this, focus your attention on legal artwork, since those artists were able to devote their full attention on what they were doing. Visit https://legal-walls.net/ to locate nearby artwork that was done by permission. Expect tagging to develop just like any other artform. This means that certain cities and regions may develop their own nuances, so pay attention to what's being done around you. Bring yourself up-to-date on local styles and trends. Reach out to local artists to find out their personal take on both the medium at large and their own contributions to it. This isn't to say that you should limit yourself to just your area. In fact, comparing and contrasting what local artists are doing versus what's being done in, say, Los Angeles or Berlin could be just as enlightening.
Research its history. Study others' handiwork. Favor legal artwork. Focus on your own area.