Get a few sticks of 5/8" dowels, cut to insert length. Buy your self a notebook, or keep notes on your computer. Start making cheap inserts, every time you do something write notes as to what happened. Then when you "think" you know what is happening every time you fix these dowel inserts you should try fixing this insert. It is the easiest way to learn the ins and outs of inserts.
Don't forget to keep notes.
Marvin