I have never tried doing stuff like this in Illustrator (yet), but it's quite easy once you have had a little bit of practice in Paintshop Pro.
You'd probably be able to figure it out on your own if Illustrator supports raster and vector layers within the same image (I don't know if it does).
If it does, I would suggest grabbing some very simply drawn sample images to work with, creating a new vector layer over them and using the sample images as your guide. You could practice getting your shapes to follow the same lines as the sample image. It only took me an hour or so to get the hang of node manipulation, this way.
I do all of mine as a series of vector circles shapes, manipulated at the node level till they are just right, converting all the nodes to "cusp" type before I begin (I just find it a lot easier to work with that way). Each circle has 4 nodes, by default (which I may or may not keep, depending on how complex of a shape is the goal). I add more nodes, as needed, remove ones not needed, drag & drop the existing nodes where they are needed, and lengthen/shorten the handles and swing them left/right till it matches the lines on my base image. When I am finished, I delete the base layer, so only my vector layers remain.
Once you have had some practice with some sample images, you can sketch & scan your own to work with, doing the same thing....or move on to photos that have very clean lines.