Watercolor is something of a mystery. The way the paint and water interact is not always predictable. That is part of both the beauty and the frustration of painting with watercolor. You have to be open to the “happy accidents”. I don’t know who coined that phrase, but it is really appropriate.
It’s often very difficult to get a natural or random look when painting certain aspects of nature. For example, I have a painting that has a lot of small twigs and branches. I was struggling with trying to paint a “natural” look for the tiny intertwining twigs when I remembered a suggestion someone once gave me to use a straw and blow the paint around. So I dropped some wet paint onto the paper and took a small straw and blew into the paint with short puffs, moving the straw as the paint ran across the page and branched out into little twigs and branches.
I didn’t have much “control” over how the paint ran, it took off in random directions and the result was closer to nature than anything I could have planned, drawn and painted. I’ve had many “happy accidents” and they are often the favorite part of a painting.