UPSKILLING IN UX

I have worked in a kind of digital marketing/web design track for the past 9 years. Due to mental health problems, I have never changed prior to the position I was assumed, although my roles have changed a lot since I started and do more technical work than I was originally accepted. In short, I did my job well enough not to be fired, but not enough to be promoted.

In the past year I got my life together and my mental health under control (Yay medication). I did much better at work and got work outside of my job description. This included what UX design work, in particular around the optimization of conversion speed.

I am not going to leave my workplace soon, certainly not with how uncertain this economy is now. But I want to work on upskilling with in UX to improve at my current job and build more tradable skills in the hope of getting a much better -paying job than I am currently doing in the near future.

I know that there are different sources for learning UX design, but in terms of building up my current work experience with conversion rate -optimization are there specific sources that I should investigate? For what it is worth, I also have a lot of experience with A/B tests on both websites and e -mail and analyzes.

I also wondered if it is worth looking at freelance opportunities to gain experience while I stayed with my current job? If it is, how should someone find such work in my position?

Thank you all for any advice!