Just wondering if anyone can give a brief overview on how to take a hand drawn image and turn it into a decent looking vector image? I have no idea where to start.

Hi everyone! I'm VERY new to using Inkscape. I already LOVE the program. Here's my issue, I'm trying to use the brush stoke tool. When I do, as I draw nothing shows up. After I draw the stroke I can then increase the opacity to 100% for it to show up. Then soon as I do another stroke, it defaults ba...