Please provide some tips for creating a new "recipe" including a package from source

[Chris Miller (MESL)]

I tried to create a new recipe which comprised "skeleton" plus "linphonec":
- I used git to clone the source for linphone to apps/linphone
- I copied the whole of  platform/skeleton to a new folder 
platform/christest
I then added the line
PKGS_APPS += linphone to /platform/christest/Rules.mk

Then I returned to my nard folder and did
make christest

But was told that Make does not know how to make christest.

So I then simply edited platform/skeleton/Rules.mk in the same way.

This time when I do "make skeleton", it enters the apps/linphone 
folder.  This fails,  but I suspect that's my fault for now, (as 
autogen.sh does not run cleanly - I need to fix that first)

so two questions:

1) What is the correct way to create a new "product"
2) Apart from knobbling Makefiles to use the correct (cross-) toolchain, 
does anything else need to be done to incorporate a new package in to 
the build?

With thanks,

Chris