Hi bud. Raf is the man, and pretty much hit the nail on the head with everything. I did indeed use Garretts (Terminal Fettlers) colour list, and made a few small adjustments to colours and processes in a few areas. To me, Garrett is one of the best colour matchers and painters on this board, so to be able to get his sort of results was fantastic. Now, as Raf mentions, I did indeed use his ESB stencils, which were made even more accurate while I was doing this paint up, and we were all able to discuss some details and collaborate. It is in my mind, without question then, that Raf's ESB stencils are nigh on perfect as the best ones out there. They are howvever, adapted to the ESB Hero helmet - or movie accurate version. Extra scuffs, scratches and scrapes happenned since the movie, to make what you would see as the current rendition for the Special Edition version.. Also remember that you may have to scale your stencils to fit your particular helmet, as every helmet differs a little in size..
So, as that is the version you would like to replicate, I personally, would approach it by using Rafs awesome stencils, and then adding the extra damage by using the high resolution images in the 'ART OF STAR WARS' Exhibit shots in the gallery. Particular places you will want to look at where there is extra detail than the movie version, are areas such as : the black scuff marks in and around the killstripes, extra white scuffs at the front of the helmet near the dent, some orange residue spots around the back and sides of the dome, and several extra scratches and silver areas on and around the red mandibles and upper cheeks. There are more, but pics will be your best friend here.. I would research and be aware of all these areas before you start the painting process - that way, you can see which new bits need to be added during the painting process, or can be added later topically. Planning it all out, is the key to success..
As for the Humbrol paints - they are mainly what I like, combined with the odd Floquil colour here and there, but with Floquils range recently shown as getting discontinued, I feel Humbrol is an excellent way to go. In fact, I am still a much bigger fan of the Wine 73 from Humbrol for the Mandibles and trim, than the often more commonly used Floquil Caboose. I feel the Caboose is perfect for ROTJ, but for ESB, the wine 73 while similar, just has a little more red value, that seems present in the hi-res images.. All mine and Garrets Humbrols were the ENAMEL versions. I prefer the enamels, and they give a lovely finish. The Humbrol acyrylics I have tried do match up reasonably nicely, and they actually seem a good quality - but they are harder to get in my area, and they definitely dont have the complete range that the enamels do. But when it comes to that type of thing, you have to go for the medium you are most comfortable with. I just cant say for certain how well the colours match up completely with thier enamel counterparts..
There you go my friend, feel free to ask any questions if needed. Peace