I think a real challenge that many people face when they start painting is that feeling of disconnect between their finished painting and the idea they had in their head. I remember in my first few studio classes, I'd be sitting in class for weeks trying to paint a (stupid!) vase of flowers and at the end I always felt like "Wow, this looks so amateur."
A big game changer is learning how to give your marks character. Looking back on my old paintings from high school, they're all so flat and one dimensional. My paintings really started to evolve when I explored all angles of my tools & brushes to make more interesting marks on the page.
For instance, look at the simple lines below just using the brush in a one dimensional way:
I'm working with the brush as if it were just a pen in my hand. I'm applying the same pressure throughout, and holding the brush at the same angle for the entirety of the brush stroke.
In this next case, I'm trying out different pressure, lifting the brush & pushing it into the page for a more interesting effect. I change the angle, using the sides of the brush, to create thin lines:
This technique is sort of awkward at first, because you're probably not use to moving the brush around in your hand while you use it. But, when you get the hang of it, you can really explore a whole new world of lines! Which is super exciting (I think it is anyway).
Try it out! Experiment with new things and make something new!