Coolies. Well here's the best set of tips I can give you then ^_^ .
When you scan the picture in, adjust the contrast to start with so that the outline is quite dark.
When you load the picture up in photoshop, open a new layer, and call this layer "outline". Now cut everything away from the background layer (Ctrl+A and ctrl+x). Paste the picture you just cut onto the outline layer.
Now you will notice, on the toolbar in the bottom right, there are 3 tabs, "layers", "channels" and "paths". Click on the "Channels" tab. At the bottom of the box now, there are a set of 4 buttons. The first one, a hollow circle, is the "load channel as selection" button. Basically, this will select every bit of white on the current layer.
If you click on this button, pressing delete will delete all of the blank areas on your picture.
You may notice that the lines become very faint. To correct this, click on the layers tab at the top of the box again. You will see just below the tab, there is a series of buttons, that come after the word "lock". Selecting the Chess board type button will lock all the transparent pixels on the layer. At this point you can get a paint brush and paint black over the picture to restore the darkness of the outline without damaging it at all.
Let me know if any of this helps you out, or if I've been unclear at any point in there. If that goes to plan, I can show you how to do some neat colouring next 🙂 .