I have been doing photo studies of landscape a lot, and mostly for the purpose of training myself to pick out the colour more accurately. Yet I found another issue occurs here is that my study tend to be blurry, especially in edges. These took about 15-30 mins. I know spending more time on them seems to be a solution, but somehow I don't think that's my case.
I use almost only the round hard-edge brush in Photoshop, with opacity 100%, flow 100%, opacity control set to pressure.
Any suggestion and and advice would be appreciated.