In replying to another thread I realized something. All us raster based cartographers should remember three concepts, working in layers, layer masks andnon-destructive editing.

Working in layers allows you a great deal more flexibility to change things later and most folks that work in in these programs pick this up pretty fast.

This project is a good example of how I used the layer masks to dictate where the forests would appear and make it easy to alter the color or look of the forests laster if I change my mind without having to re-do them.

Non-Destructive editing is something that people that learned in paint programs and hand drawing often have some trouble getting thier heads around.

The idea is that if you want to change the color of a layer, you can either re-paint it with a new color or add an adjustment layer to tweak the colors. The primary difference between the two methods is "Undo ability". If you realize the change was a mistake reasonably soon after you do it, simply undoing it will work fine. But if you realize it after you've already done something else that you don't want to loose or that step is no longer available in the edit history, you'll be stuck. But if you used the adjustment layer it's a simple matter to readjust it or remove it entirely.

I see photographers doing this the worst. They like to adjust the brightness and contrast of an image and find an option for that in the menus of Photoshop. However they end up permanently adjusting the image this way. If they used an adjustment layer they'd be able to adjust it later or even apply a layer mask to limit it's effect. Undo is handy but it's not exactly a time machine.