Firstly, It's all about the water to paint ratio. In fact, it is much about learning the properties of water as the properties of color.
This is a BIG DEAL: Paper: Use the good stuff. The cheap stuff will frustrate you.
Thirdly, If you mixed mud, figure out why. Was it the colors you used or too much scrubbing. Pay attention to the mud. It is useful. Mud is not always a bad thing. It makes clear color ring.
Ultimately ... Play = Practice. It's the same thing. If you take a playful approach to practice, your mind will remain open to letting in all sorts of new observations.
One of the reasons I put this together for you was to let you into one of my online classes in a small way. To give you a taste. You may feel more comfortable laying out your hard earned money on one of my future classes (online or in person).