This article was written in 2015. It might or it might not be outdated. And it could be that the layout breaks. If that’s the case please let me know.
Johan Huijkman answers the question if accessibility is that easy, then why doesn’t everybody do it? by breaking the WCAG checklist down to four points: keyboard, semantics, screenreader and colour. If you make sure those are fine, your app is much more accessible.
And remember: your app will be even better if you apply these four points with this this simple rule in mind: accessibility is about everybody.