I think John Muir Laws has a good tip for blotting brushes. He cuts the foot part off of an old sport sock and uses the cuff on the wrist of his non-painting hand to blot his brushes. My only thought of caution would be if some of your paints contain irritants or heavy metals.
It has been many years since I picked up a sketch pencil, paints or brushes. Life has a way of throwing in a host of other priorities. I'm taking this course to bring my desire to journal to fruition. I've never stopped hiking or taking long walks. In the past it has been mostly photography that has supplemented my learning and love of nature and biodiversity.
Reading books like The Forest Unseen, by David George Haskell or Birds by the Shore, by Jennifer Ackerman have helped me immense myself in nature during my walks. I take notes and some photos in the field, and also do some light sketches. Later at home, making entries into my journal will help me capture the day and my observations, and motivate me to research further. Never stop learning.