A mistake I often see in the layout of academic publications: The line length is too wide.
The text is stretched wide upon the page, and the margins are too narrow. This forces the reader to ‘jump’ off the end of the line, searching for the start of the next one. It fatigues and slows down the reader (or makes them give up entirely).
For longer texts, you should aim for between 8–13 words per line for comfortable reading.
The white space of the margins is, in a very real sense, a comprehension tool. Be careful not to crowd the page if you have to adhere to a standard printer paper size, such as A4 or US Letter. Leave some room for the eye to rest.
Don’t set the column too narrow either. A large newspaper page with different articles across many columns is another story. For optimal reading of a professional paper, you use the space available. Both for presenting text and figures, but also for some breathing room.