Regardless of the size and niche of your business, you have to spend on designing a website, and probably an app. UX design is critical for all brands alike, and if you are planning an ecommerce site, this is even more relevant. Hiring a known UX design agency is easy, but what needs attention is how you collaborate on the project.
Every website is unique, and therefore, it is necessary to have clear expectations and scope of work. If you have liked a few websites, or would want your site to look a certain way, make sure that the agency is aware of that. The process of designing involves many steps, so the agency will seek your inputs and approval as required.
If you want to evaluate the experience of an agency with regards to UX design and web development, you have to check their clientele. Get references and recommendations, and check what their clients have to say on Google. Discuss your work based on their expertise, so that you manage your expectations accordingly.
On the last note, stay involved. Both UX design and web development require collaboration and constant communication, so you need to be accessible, as well.