first off, hello! Been signed up for a few months lurking here and there (mainly in the finished map forum), and admiring (and developing a sincere jealously of) peoples map making skills.
So here's my situation -
I've been developing for a while now a conworld for a personal writing project. I have a fully drawn out world-map outline which I drew by hand and then traced into photoshop (http://img12.imageshack.us/img12/8225/finaloutline.jpg) , and one continent of which I have made detailed hand-drawn maps, and fleshed out quite detailed geography, topography, and biome distributions etc.

Basically I would like to go about making a reasonably detailed world map (which details the main geographical features of the planet like major mountain ranges), and then make one continent much larger and much more detailed, with labels for different tribes, roads, and territories etc. I must note also, that i've got absolutely no photoshop experience, and am currently wading my way through the very boring photoshop basics tutorial mentioned in the tutorial forum, so forgive me if I seem incredibly foolish.
The first problem I've come across is scale, and how to keep the scale right when copying one of the continents to a seperate document and trying to enlarge it. Basically I want one of the continents to be much larger and on its own document, but I want to retain its shape and so forth from the world-map view. So far, when trying simply to use the 'scale' function, I get a wildly out of proportion view. Any ideas?
Secondly, are there any tutorials dealing with designing a full world-map? I can only seem to find continent based tutorials at the very most.
Thirdly, any general advice or ideas about anything i've mentioned which might help would be greatly appreicated.
Lastly, I'm glad I found this place, and it has awoken in me a desire to be able make maps that look as good as many on here!