@FreeMind @StanShunpike probably the best quick book full of useful *methods* is this weird book
http://books.google.ie/books?id=jUsv4aGmIUsC&printsec=frontcover#v=onepage&q&f=false
There is literally no other book as good as this for quick and dirty methods, if you read that you'll just about have no problems tbh if you want to go deeper there is an old book by Ince called Ordinary Differential Equations which explains things properly but is a bit crazy. If you don't believe me, there is a book by Murphy called 'Ordinary Differential Equations and Their Solutions' which lists just about ev…