Headings – Making sure that you are using H1, H2, etc. tags properly so that readers can organize the sections properly.
Contrast – Most designers know that text needs to contrast with the background, but making sure that the backgrounds of different sections contrast with each other enough to make them distinct is also important.
Link Text – Common phrases like “click here” can be extremely ambiguous when being read out by a reader. Especially if there are multiple of them.
Labels – A label that is properly labeled as such in within the HTML is important. Simply putting a span or div adjacent to the input is not enough.
Tota11y will help with more than just the issues above. Problems with these can make navigating your site difficult or even impossible for some of your users. Correcting these problems is often easier than you might think, and is obivously the right thing to do.