You already have a personal brand.
It is not your logo, it is what people think of when they see you. What they expect and what you reinforce by your patterns of automatic behavior. That is your brand. It’s how you behave, how your materials look, how you treat time, people, and your work. All of that already projects to others the kind of professional you are.
Do you want to change it?
Knowing what to do is easier than doing it. And you don’t have to do it all at once.
Here’s what you can do to begin:
Identify one characteristic about you that you are proud of, that is unique or special to you, and would be seen by others as valuable or attractive in some way.
An example for me is that I have education and expertise in two overlapping fields: business and human relations.
Start communicating it to the world in a tasteful, consistent, persistent way. It can be part of your personal description, or part of your website, and certainly part of the value you deliver to your clients. Craft a sentence that tells people about it in a way that is comfortable for you. Say it regularly and live up to it always.
After a while, that attribute will become part of your brand. It will be what people expect to see, and it will be what you deliver.
Are you conscious of the value of your personal brand? Can you list the key attributes you want people to associate with you?