Hey, thanks for visiting I'm Yahaya a Web UX Product Designer, I've been in the web field for about 15+ years, during that time I helped define and improve the UX on web products, from small static sites to multi-million visitors ones.
Generally speaking, I starts with defining what is the purpose of the product and defining product KPIs, once those are set. I define the user's journey build wireframes and prototypes and get initial feedback through user testing. Iterate on necessary areas and define main tracking points, go live keep look at the data, do more user testing and iterate
Defining products features and user's flow
Getting prototypes ready for user testing and gather feedback as early as possible help prevents complications further down the line
Having a working product is one thing, but making it shine always adds value.
I'm a true believer in the Principles Behind Agile Manifesto, check them out if you're not familiar with them