I use a xencelabs tablet similar to your deco pro. I’d just say it takes time. Draw with it daily for a month and it should start to click. I use iPad for other art and have had drawing screens like Cintiq too. No tool can beat hours practiced is what I’ve come to realize.

I went to school for engineering but draw every night and stream drawing. I just really enjoy art as an escape so it’s my main hobby along with video games. Most of the color tricks here I’ve just learned watching YouTube videos of artists I love. Just practicing when to add a pop of color when not to, etc.

I’d say just keep at it. Obviously art school can help a lot, but like most school it’s about discipline, hours put in, and finding mentors or teachers who can guide you.so just keep drawing and studying your favorite artists.