Search for an existing article
The English Wikipedia already has 5,737,009 articles. Before creating an article, try to make sure there is not already an article on the same topic, perhaps under a slightly different name. Search for the article, and review Wikipedia's article titling policy before creating your first article. If an article on your topic already exists, but you think people might look for it under some different name or spelling, learn how to create redirects to alternative titles; adding needed redirects is a good way to help Wikipedia. If you're not already autoconfirmed, you can request a redirect to be created at Wikipedia:Articles for creation/Redirects, where a volunteer will review the request, and if it seems like a plausible search term, accept the redirect request. Also, remember to check the article's deletion log in order to avoid creating an article that has already been deleted. (In some cases, the topic may be suitable even if deleted in the past; the past deletion may have been because it was a copyright violation, did not explain the importance of the topic, or on other grounds addressed to the writing rather that the topic's suitability.)
If a search does not find the topic, consider broadening your search to find existing articles that might include the subject of your article. For example, if you want to write an article about a band member, you might search for the band and then add information about your subject as a section within that broader article.