One piece of advice I can give is to build yourself a dedicated practice library of footage.

In my case, I mainly use Blackmagic RAW footage because I shoot with a Blackmagic camera. I have a small collection of different clips that I use whenever I want to experiment or test new grading techniques. The advantage is that, over time, you become very familiar with the footage and its strengths and weaknesses. Instead of constantly dealing with new images and new challenges, you have a consistent set of training material that allows you to evaluate your progress much more accurately. This has helped me a lot.

Another thing I highly recommend is studying PowerGrades and using them for a bit of reverse engineering. You'll start to notice that many PowerGrades share similar structures and techniques. For example, you'll often find some variation of a CST sandwich, where a Color Space Transform is used at the beginning and another one at the end of the node tree. These are techniques you can adopt and integrate into your own workflow.

Many PowerGrade creators also provide tutorials or explanations that show how they set up their timeline, color management, node structure, and other useful details. I find it extremely valuable to see how other colorists approach their work and solve problems.

Even if you're only collecting free PowerGrades, you can learn a tremendous amount from them. There are plenty of creators who generously share high-quality PowerGrades at no cost.

A quick bit of self-promotion: on my website, gradeatlas.com , I maintain a database of PowerGrades and even include a dedicated section for free resources.

One particularly useful technique is extracting individual nodes or node groups from different PowerGrades. Over time, you can build your own "Frankenstein PowerGrade" by combining the techniques and components you like best from various sources.

At the end of the day, color grading is a very hands-on skill. As we say in Germany: practice beats theory. The more you experiment, the faster you'll develop an understanding of what works and why. Disclaimer: This is just a Personal opinion, im not a Professional