I made the mistake of trying to let a movement down with its own key once, it slipped from my fingers and span around knocking the top of my knuckle clean off. Mainsprings are not to be meseed with and if starting again knowning what I know now the first tool I would buy would be a set of let down keys.
This is such a great hobby/business to be in and having gone through life with nothing holding my interest for longer than a few months this is amazing, there is so much to learn and the pleasure you get from getting that old wreck of a clock working is fantastic.
We are all here to help and never be affraid to ask, we all remember what it was like when starting out 
Paul.
