Error prevention on important forms (3.3.4): For pages that create legal commitments or financial transactions or any other important data submissions, one of the following is true: 1) submissions are reversible, 2) the user has an opportunity to correct errors, and 3) confirmation is available that allows an opportunity to review and correct before submission.
While the U.S. Department of Labor's (DOL) Office of Disability Employment Policy (ODEP) does not enforce the ADA, it does offer publications and other technical assistance on the basic requirements of the law, including covered employers’ obligation to provide reasonable accommodations to qualified job applicants and employees with disabilities. For a quick overview of the ADA read “The Americans with Disabilities Act: A Brief Overview.”
This title outlines the administrative processes to be followed, including requirements for self-evaluation and planning; requirements for making reasonable modifications to policies, practices, and procedures where necessary to avoid discrimination; architectural barriers to be identified; and the need for effective communication with people with hearing, vision and speech disabilities. This title is regulated and enforced by the U.S. Department of Justice.
Input Assistance: When users are entering input into the website, any input errors are automatically detected and written out, providing, for instance, text descriptions that identify fields that were not filled out or data that was in the wrong format. The website also provides suggestions to fix the errors. Input fields and buttons are labeled to provide their functions and instructions. If the user’s input is being used for legal purposes or financial transactions, then the user must be able to reverse submissions or correct errors.
Web designers often design in such a way that does not allow the user to adjust font size or color. While they may be protecting their brand, they are also inhibiting some users. Many visually impaired need to use high contrast color settings or very large fonts to read a website. Don't design your website in a way that makes it impossible for them to do this. 
ADA website compliance is about making sure that everyone has equal access to all the elements on your website and apps. That may mean you need to provide alternatives for some of the functions and content on your site in order to meet ADA website compliance standards. Here’s a quick rundown of some of the accommodations that need to be incorporated into your website to meet the ADA guidelines:
The ADA has been criticized on the grounds that it decreases the employment rate for people with disabilities[48] and raises the cost of doing business for employers, in large part due to the additional legal risks, which employers avoid by quietly avoiding hiring people with disabilities. Some researchers believe that the law has been ineffectual.[49] Between 1991 (after the enactment of the ADA) and 1995, the employment rate of men with disabilities dropped by 7.8% regardless of age, educational level, or type of disability, with the most affected being young, less-educated and mentally disabled men.[50] Despite the many criticisms, a causal link between the ADA and declining disabled employment over much of the 1990s has not been definitively identified.[51]
What services they offer. Make sure the web design agency you’re interested in offers all the web design services you’re looking for — like 508 compliance, ecommerce design, or CMS integration. You’ll also want to see if the agency provides other services like SEO and PPC. You’ll likely be interested in these services after your website is up and running, and it’s extremely beneficial to work with a web design agency that does it all. You’ll want to be sure that the agency you choose provides other services like SEO and PPC since a great website is essentially useless without the proper promotion.
So, what do I mean by that? That sounds weird. So, when I say designer, I mean someone who's strictly an artist, and there's a lot of those out there. A lot of 'designers' are only concerned about the aesthetics of the site. What it looks like, or if its unique, or if it follows the latest website design trends. But at the end of the day they don't really 'get it' when it comes to what the primary purpose of a website is.