As you have discovered, supporting a website and continuous improvement efforts are an "ever-growing job" and in fact, never-ending. For all of the hard work, and even more for seeking suggestions for improvement from others.
Rina, Aamina, Michelle, Jeff, Bennett, and Patrick all made excellent points for consideration. To not re-hash their thoughts too much, following are some more basic "block and tackling" considerations.
1. Regularly scan for broken (or not performing links) and resolve them. Examples are:
- In https://www.lastchanceautorepairs.com/auto-body-shop-plainfield-naperville-bolingbrook-il/ there is a broken link
- https://www.recommendedcompany.com/b/81ys.gif, likely resulting from a certificate issue on the target domain.
- In https://www.lastchanceautorepairs.com/hyundai-clutch-replacement-week-in-plainfield-il/ there is a broken link
- http://lastchanceautotransmissionrepair.com/, likely resulting from the absence of https://www in the URL.
- In https://www.lastchanceautorepairs.com/ there is a broken link
- https://www.hubgarage.com/mygarage/LastChance, resulting from a 404 not found error.
- An example is https://www.lastchanceautorepairs.com/auto-air-conditioning-repair-plainfield-il/ (line 971).
2. Review potential browser compatibility issues, such as:
- Internet Explorer, Chrome, and Firefox display a security warning when a secure https: web page includes http//: content.
- In IE8 and Firefox 23 onwards, the default option is not to display the http:// content.
- To fix this, use relative URL paths ../images/file.png, or full URL paths /images/file.png; or absolute https URLs https://example.com/images/file.png.
- An example is https://www.lastchanceautorepairs.com/auto-repair-services/ (line 747). Also, consider replacing flash multimedia content with MP4 (recommended).
- Older browsers do not support SVG images (e.g., Android 2 or earlier). An example is on https://www.lastchanceautorepairs.com/ (line 2509).
3. Search Engine Requirements
- Do not stuff alt text with keywords that users are unlikely to view. Doing so may result in search engine penalties. Example: https://www.lastchanceautorepairs.com/auto-air-conditioning-repair-plainfield-il/ (line 1271)
- Google and Bing recommend avoiding broken links. Example: https://www.lastchanceautorepairs.com/brake-repair-naperville-il/ reference https://www.lastchanceautorepairs.com/wp-content/uploads/2011/04/Performance-Brake-Repairs-In-Naperville.jpg (line 771).
- Bing recommends that each page should not have more than one h1 reference element, e.g., https://www.lastchanceautorepairs.com/auto-battery-replacement/ (line 773, 774).
- Bing webmaster guidelines recommend that each page have one h1 element. An example with the h1 missing is https://www.lastchanceautorepairs.com/category/blog (line 74).
- Strongly suggest that you consider using the Yoast WordPress SEO tools, if you have not already.
- Review: W3C HTML/XHTML Validation and W3C CSS Validation
- In many cases, these best practices revolve around keeping up to date with coding standards and replacing obsolete features as needed.
- Example: The align attribute on the p element is obsolete. Use CSS instead. When using WordPress, make sure you're plug-ins are up to date and if one doesn't get the desired results, switch to a more technically up to date plug-in.
- Review accessibility features against the standards of WCAG 2.0 and Section 508.
- Non-compliance can result in issues for older users, people with disabilities, or accessibility needs. Human testing, along with input from automated tools needs to be used to evaluate Accessibility.
- People with these kinds of requirements may not need your site's services :). That said, Accessibility is a pretty big deal, especially particularly with government users and web sites.
6. Regularly review web site performance
- There are many complexities to evaluating performance and excellent resources out there available at little or no charge.
- A tool that we like is https://www.webpagetest.org.
- Some hosting providers are better than others, especially for optimized WordPress sites.