Mountain Waterfall

I gave Bob Ross' Mountain Waterfall painting a go. I had done this painting in the late 80s with the Bob Ross season 5 book, which I received as a Christmas gift. Believe it or not, I still have that painting, which was completed on a small canvas board so many years ago Figured I would try it again. I just got back into painting a couple of years ago, after having taken a break from it for about 20 years; so it was fun to try one I had attempted when I was a child.

I was happy with how the painting turned out, except for the foreground bushes. I have struggled with this part of technique in almost all of my paintings. Any suggestions the Two Inch Brush community can provide to help with this portion of the painting would be greatly appreciated. I'm not sure if my paint is too thin, too thick, or what the problem is. Today I used thinner to thin the paint that I applied for the bushes. I know that liquid white could have been used as well, but it changes the color slightly. I know the golden rule is that a thin paint will stick to a thick paint. Is there a good tutorial online that discusses this perhaps??

UPDATE: Thanks to your suggestions, I went back and made the foreground bush highlights brighter and used the half round brush rather than the 1" brush. I uploaded this 2nd attempt, which I was much happier with. I also uploaded my attempt at this painting from the late 1980s when I was a child. It was fun to do this one a second time as an adult.