Years ago I decided I wanted to do a lot more creative stuff -- at school I was envious of the ease with which a friend of mine could draw -- and a book I found which helped me was
Drawing on the Right Side of the Brain by Betty Edwards. As the title suggests, it heavily subscribes to the left side brain = logical, right side brain = artistic idea, which I think has been since debunked, but I found it very helpful, not least as the book is full of what might be termed before and after sketches by her (?mostly adult?) students showing incredible improvements in technique in only a matter of months.
One of her exercises is to copy a line drawing,
Portrait of Igor Stravinsky by Pablo Picasso but
have the image upside-down -- your brain then has to look at the lines and copy them as they actually are not as you think you see them, if that makes sense. I tried and was surprised at how much better my effort was when done that way, and after some further exercises I ended up doing a line drawing of my husband's profile, which I was really quite proud of. She also talks of drawing the negative space and perspective and the like, but she's also good at building up one's confidence and explaining how to "see" -- I think the thing that sets many artists apart is that they really
look.
I didn't progress very far, largely because I didn't put in the work needed by way of continual practice -- I don't have the temperament to do exercises for the sake of doing exercises, and I want to be doing, not trying to do -- and also because I knew I wouldn't be good enough, not in my own eyes. I firmly believe that just as with writing anyone can be taught to a certain standard, but beyond that it's necessary to have some innate talent, or at least the fixed determination to put in real hard work. However, in my case I found an artistic medium where my lack of drawing skill didn't prevent me creating work that gave pleasure -- so even if you don't think you can draw, don't give up the idea of making art in other forms.
Speaking of drawing skill...
Not the greatest of drawings, is it? It's
Carpenter by Vincent van Gogh. He got better.