Hadden,
I could always draw ships...sailing ships... and have done a lot of scrimshaw work on whale ivory and horn. But I never tried to draw much else. I did spend a lot of time tracing all sorts of engraving just to get my fingers used to the shapes. Once you have a few mechanics of how to drive the graver through metal, if you can sketch the design, you can cut it.
I will also tell you that I recently purchased a book called "Drawing on the Right Side of the Brain". I have not delved too deeply into it yet, but the author (Betty Edwards) has an incredible section on the tremendous progress that can be made in just a few weeks using her technique (lots of real examples of students who went from very child like drawings to very impressive drawings in one or two months). The book was very inexpensive (used, paperback, Amazon...some used copies for less than a dollar) and I can tell it is making a difference in my work almost immediately. I would recommend it highly.
Dave C