Here is a straightforward look at this topic for Malachain.
Accessibility is often treated as a large project, yet most improvements are small and can be made page by page. Start with the basics: enough contrast between text and background, descriptive link text instead of vague phrases, labels on every form field and captions on videos. Each fix helps people with disabilities and usually makes the site easier for everyone.
Test with the tools you already have. Try moving through a page using only the keyboard, zoom the browser to two hundred percent and check that nothing overlaps, and switch on the screen reader built into your phone for a few minutes. Keep a short list of problems found and fix the most visited pages first, then make the checks part of every new release.
The most useful step is usually the first one. Pick a single suggestion, try it for a couple of weeks, and then decide whether it is worth keeping. Small, steady improvements last longer than ambitious plans that are hard to maintain once everyday life gets busy again.
It also helps to talk the subject through with friends or colleagues who have tried something similar. Their experience points out the details that guides leave out: how long things really take, which costs were unexpected, and which shortcuts turned out to be a mistake.
There is more to learn on this subject, and the linked website goes into greater depth. Treat this article as an introduction rather than the final word, and check any important decision against up-to-date, reliable sources before relying on it.