I notice many, many, many crappy skins on PMC nowadays. I'd be OK with a newer person posting something less than average, but it's just that obviously less than 10 minutes was spent on these skins. They can be pumped out a dozen a day, and it's starting to make me angry. We have skinning tutorials, but this is one of the few (maybe the only one) that focuses on beginning skinning. Here's how.

1. Start with SkinCraft/MinersNeedCoolShoes. DO NOT STAY WITH THESE FOR TOO LONG! Use the premade parts for inspiration for your own unique designs. Try not to COPY them, but alter them enough so that it's original.
In this stage, make 5 WELL-THOUGHT-OUT skins before moving to step 2.

2. Start with completely flat color. Don't try shading just yet, bud! Before you start the technical stuff, try to find your style. If your jacket doesn't look like a jacket before it's shaded, it DEFINITELY won't look like a jacket after it's shaded.
In this stage, make 10 WELL-THOUGHT-OUT skins before step 3.

3. Start to try shading. I recommend, for this stage, that you HANDMAKE a skin in SkinCraft, and simply shade it in GIMP. Do NOT use their parts--make the skin yourself on it, and use the GUIs they have and the previewer to help out. GIMP is just the program I use; really anything that has a smudging tool and a zoom-in will do just fine.
In this stage, make 15 WELL-THOUGHT-OUT skins before step 4.

4. You're on your way now! My tip to you is to search around for flat-colored skins and add some shading to them. Do NOT re-release them to PMC, just keep them on your computer, or even delete them when you're done, if you'd like to. This will help you practice shading without spending an hour making a skin to shade.

And now you're on your way to being a skinner PRO! :D Don't forget who got you here! Notice I capitalized WELL THOUGHT OUT skins. Don't make skins as fast as you can so you can move on, take at least an HOUR for whatever number step you're on divided by two. Have fun!