One article image may appear as a wide banner, a square thumbnail and a social preview. Compose the important details so each version still makes sense.
Describe the subject, background and visual style before specifying the wide canvas. Ask for the main subject near the centre with clear margins. If the title appears next to the image in your theme, leave typography out of the illustration so a crop cannot cut a word in half.
Preview the result at the smallest size used on the site. For a guide about choosing a hosting plan, a readable server illustration can work better than tiny labels on a mock dashboard. Check contrast and add concise alternative text when the image conveys information.