I found a good quality image of a logo just by googling "N7 logo", but it should work for any.
For stencilling, I use airbrush stencil sheet. It usually comes in a roll and is available at most good craft stores.
One tip is to cut an area a little bigger than the stencil and tape newspaper around the rim, one roll can last a long time :thumbsup
It's a good idea to let any previous coats of paint or clear to be fully dry before stencilling, and this tute assumes that that is the case. Right, here we go:
Scale the logo pic to the size you need and print 3-4 copies, one trace cut for each composite colour (your assentially breaking the logo into its componant parts and reassembling it in stages), and one for referance to help align them up nicely.
Lay each of the logo prints over the top of the stencil sheet so the stencil sheet gridwork (the bit you peel off) is face down, and cut about two inches around the outside of each logo.
Once each piece is cut from the stencil sheet, secure the logos in the centre of ech piece (photo mounting glue is a good way of doing this, it won't slip about, or go elf shoes on you and curl up like paper normally does), and allow to dry for a bit with something flat n heavy on em.
Take each piece and carefully cut out any sections that share colours, and repeat for each colour, these are your composite stencils. Using the guide print, peel the backing off and carefully place and secure in the desired location.
!!Check twice, spray once :thumbsup It's no fun finding that spot you didn't notice was exposed and ruining your lovely paintjob.
After the paint has set a little, but not hardened (and hour or two in moderat tempretures is about right), carefully peel off the stencil and leave it for the recommended full cure time, and repeat process for each colour.
Once complete and fully dry, include with any weathering detail you might be planning, or just seal with the clear coat of choice for that shiny new look
*edit* for single colour logos, only one stencil is needed.