AEM afr gauge wiring

Ordered an aem afr gauge (AEM 30-0300) that should arrive soon.
Think i have to hook up a 12 volt switched source + ground. Whats the best way to hook this up. Some says directly to the fusebox but i think upstream with a inline fuse to the fusebox would be better. So where to you guys get your ign 12 volt + ground. Pics would be a appreciated.

THX

i use one of those and the directions were pretty clear and complete.if im not mistaken ( its been awhile) i just hooked it up to a switched source.wait till you get it and see what hey want you to do and if you have any questions ill look at mine and try to be more helpful