Yah, I'd really recommend cleaning up. It's a good (and really simple) way to make things look better, if you're going to upload 'em. See, they could be pretty nice, but they're so dirty and uncontrasting that it distracts from the pictures themselves - like if you need gla-sses but don't wear them. Everything ends up as just kind of a mess that's hard to take in. Even if you try to stare and really see things, it'll never look quite as good.
Big difference between this and this.
Usually what I do is take my drawings into a digital program and do a lot of sharpening and noise-reducing. There are probably better methods out there, but it works. Just keep doing it back and forth until you're happy with the result - experiment with it to see how much is needed.
And you should make sure your drawings are clean before they're scanned too. Erase any smudges or grey spots you see, and try to get the lines dark and clean if you're going for the whole.. outlined thing. Maybe if the side of your hand is the problem with the smudges, stick a sheet of paper under it while you're drawing. That way it can't grab hold of things you don't want going anywhere.
Also, you seem to be afraid of shading. There are a few darker bits in there, but they're just.. almost not visible. Don't be afraid to lay the lead down if need be. Get a good, wide range in there if you're going to use one at all. A good way to get this down is to find something simple, like a cup or ball, and just. Draw it.
Since there are no details to worry about, it'll be all about the shading.