Here are some pictures using the "hinge" method which I find the easiest to use. This is how I placed some older saddlebag graphics on my 2012 Electra Glide. This method can be used with almost any decal. Here is a video that shows an excellent technique, its not mine but you get the idea!
https://www.youtube.com/watch?v=ItodhIEVWT4
https://www.youtube.com/watch?v=ItodhIEVWT4