This is the process I usually take but it changes depending on the project and deliverables:

I would first gain an understanding of the user base and I could use several methods like acquiring knowledge from the existing data the client has or I could set up a short survey of about 10 - 15 mins to gain a more in-depth understanding of the users including their demographics, behaviors and pain points. This could be a Google form or any tool the team uses. This survey would help inform about the personas.

The personas would be grouped based on several factors like needs and behaviors, more research would be done, in this case, qualitative research like an interview to have a deeper understanding and distinguish between actual needs from minor inconveniences. This would also help see where product improvements can be made.

A list of the core user needs and pain points would be drafted and a couple of product improvements and refinements would be suggested and all this is while keeping the business needs and the team's skillset at the back of the mind.

This is usually where stakeholders steps in and the list of core user needs is narrowed down into what makes the most sense from the business perspective, the developer's standpoint, and also what is achievable given the constraints like time and technology.

With the list down to just 2 or 3 features, I start wireframing solutions and creating high-fidelity prototypes to be tested by users.

The prototype is tested by users and more feedback is gotten as regards gaps in the product.

A couple more iterations down the line and the product is ready to be handed over to the developers.