As far as I know, you only need to contact the company that provides these services, for example https://fuselabcreative.com/ , they have a good reputation, they have examples of works on their website. Next, they will look at your site and tell you what you need to change or you will begin to discuss the design of the new site. They will tell you about new trends and how it affects the promotion of your site and user friendliness. This will help you choose what you need. You can also consult with them about the promotion of your site. I was very worried when I turned to them, because I don't understand anything in design. I didn’t know how to answer if someone asked me something specific. But it was not so scary. Real professionals work there who can explain the essence to you in simple words, but the choice is yours.