On a day when you are not painting/drawing, but still feel you should be doing something to push your skills forward, you can do the following exercise to hone your value observation skills. However, you will need a smart phone for this exercise.
Get a bunch of color cards/swatches from the local hardware/paint store. As shown below.
Take any two color cards, from the bunch, and match the values to the best of your abilities saying to yourself if they are equal in value or different, and if different which one is lighter and which one is darker. You need to have a color isolator, which is essentially made of black paper (or use one of the black color cards) with a cutout in the center. The color isolator isolates the two colors to compare the values, as shown below.
I have an App on my (iPhone) smart phone: “Black + White Camera HD” by SixAxis LLC. This is a wonderful app. that delivers a B&W image on my phone screen and I don’t have to snap a picture. I keep my Auto-Lock set to “Never” so that the Phone remains turned On during the whole exercise (and I don’t have to enter my password every few minutes to get back in). This way I can whiz through comparing the color cards.
Simple! You don’t have to use any drawing/painting tools for this and off course no color mixing.
At first, when you are starting out, you may want to compare a B&W card with a color card and when you feel comfortable, graduate to comparing color cards. I am sure you will come up with your own creative ways and if you do please share it.
Off course, you can use any digital camera and do not need a smart phone or an app. It is just that smart phones are so convenient and almost every other person has them.