We're going to give this a try. What would you like to know about the art of faking?? We have numerous fakirs here, of varying skill levels, so someone is bound to be able to point you in the direction you wish to know.
I'll start out by stating some very basic tenets of faking.
1. Choose a HS (head shot) that somewhat resembles the HS of the body model.
2. Watch your lighting. If the BS (body shot) is taken outdoors, don't try to place a HS of a celeb taken inside.
3. If the BS and the HS are pointing opposite directions, vertically flip the BS, not the HS. Celebs facial features are very recognizable, if you flip the face, it's going to usually look awkward.
4. Choose a HS that is larger than the BS. It is always better to downsize the head to fit the body rather than expanding the HS.
5. Hairstyles make the celeb!! Try to use as much of the celeb's hair as possible.
Save your work often!!
The more layers you use, the easier it is to correct mistakes. Layers are a bit confusing, hell, I'm not good at it yet either, yet once you learn how to use them, it'll open the door to creating very intricate fakes.
Make a logo or signature for your work. This is a bit of a holdover from back in the day when guys were afraid their work would be passed off as being real, and the law was unclear whether faking was even legal. (Thus why a lot of the older fakes have a disclaimer saying that the fake is a parody... fakirs were covering their asses). But it's also a matter of pride. You've created this thing, sign the thing... be a part of the community.
Most of all, don't be afraid to ask for help or advice. Most fakirs want to share their craft, and those that don't won't say anything anyway. So ask!!