Strategies for Finding Freelancing Clients?

I'm thinking about transitioning to freelancing, but finding clients has been a challenge, especially on platforms like Upwork and Fiverr. I’m confident in my web development skills and believe I have a lot to offer. For those who freelance, how do you typically find clients? Do you focus on creating standard websites or take on more complex projects? Also, is it better to specialize in a specific niche or stay versatile?