I have spent much of my summer studying one of my biggest challenges... value.
Value in art is the relative lightness or darkness of something. It is the basis for how us humans identify form. I have come to realize that I am often distracted by color and do not accurately identify values. This leads to unclear observations. Hence... time to slow down and put on my thinking cap!
There are many ways to 'hone up' on your values. Using a red filter is a common one. The red absorbs all color wave lengths except red, leaving your view only to black and red. However helpful that this is, there are still a huge number of values left to put in order, which can be confusing. For this reason, it is common to work on choosing only a few 'grays', or values, to classify all shapes into. It comes down to making choices... just a few shapes and just a few values.
This is a time to not worry about a 'painting', but to look in depth at simplicity and accuracy. Simple shapes and values. Give yourself permission to slow down and truly observe.
From here there are many ways to advance your understanding of value. I recommend, however, sticking to this simple practice until it truly makes sense to you. After a full summer of careful observation of values, I am enjoying a new awareness and skills that I have developed throughout my summer of studies!