I've been sketching all of my life pretty much (obviously I'm better than when I was 3 ) and I really want to get into digital stuff, like you. I just need the supplies...
Basically from what I've seen in videos (and personal experience with airbrushing) you'll want to do the main 'filling' colours first to fill the scene. Then, work your way around adding detail and lines. Finally, add some shadowing. Not exactly sure if this is right, but seems like the way to go.
Very cheap (compared to say, Wacom tablets, which run up in the hundreds). It works fine, just like a mouse and can be used in any application (obviously, it's designed for Photoshop, etc).
I don't know how much you can accomplish in Paint, but the steps to digital coloring in Photoshop are easy:
1) Draw your picture on paper
2) Scan as a large JPEG, etc, onto your PC
3) Open the scan in Photoshop, do any necessary resizing or cropping (Image > Image Size, Image > Crop)
4) Double-click your line drawing layer (which should be the locked background) and click "OK" on the little Window that pops up. This makes it a regular layer ready for editing
5) Now, to remove the white background (from the paper), select the layer and go to Image > Adjustments > Brightness/Contrast. Increase the contrast until your black lines and white background are very ... contrasting. Then go to Select > Color Range and pick whites. Hit OK and then hit delete (this step can also be accomplished by selecting a white region with the Magic Wand, right clicking in the region, selecting "Similar" from the drop-down menu and hitting Delete. Now you should have a layer with only your lines and the rest transparent
6) If you don't already have one, create a new layer and fill it with white (as your new background) using the Paint Bucket
7) Your picture is now ready for coloring. Simply create as many new layers under your "Line Drawing" layer and above your "Background" layer as you want (ex - "Skin", "Armor", "Hair"), and proceed to fill in each area of the drawing with color using the Paintbrush
I have no idea who actually has Photoshop, but this is a useful tutorial to post here for anyone who does. I really don't know how far you're gonna get with Paint. Just know that Photoshop provides painless coloring and is worth it if you're serious about digital art, etc
Hope this maybe helped somebody,
Oh by the way, nice Stormtrooper! And why is this in "Armor Related Videos"?