Trigun
So, I found the highest quality scan that I could and then vectorized it. Hopefully that took care of all my quality issues. Again, do I have the basis of a potentially good paper? Does the font work? Is there not enough? Does the color scheme work?

Well...

The quality of the scan doesn't matter if you're going to filter it out like that. Filtering out the character like that defeats the purpose of a vector. I am not sure if you're confused with what a vector is.

A vector is a shape made of calculated paths. The advantage of a vector is that you will get crisp lines and you will be able to scale the shape bigger or smaller without losing any quality. When you over-filter like that it just becomes another regular image.

Overall the wallpaper is lacking quality. The background is blurry and artifacted (blocky). Which looks like the result of blowing up an image beyond its original size or a bad scan.

Composition-wise it works out. I would move "Trigun" a bit more toward the top right corner to even out the negative space around it.

I suggest keeping the character scan in its original state and use layer effects or a filter to blend him into the paper. Then you will need to re-scan a crumpled piece of paper or learn how to render a crumpled piece of paper. Unless I am blind I see the lack of a signature (your animepaper name).

The wall is a little too small for a "vector" wallpaper. And as the background is very simple you should add some more effort in it.

Indeed the character vectored or not doesn't fit. Why don't you try to give to him a draw feeling instead of some impressionism look?
You'd better start back with the scan and make it in grey scales like you were drawing it with a pencil. You can even add some light lines of pencil to him so he looks like you really draw him... Sketch looking!

For the background I suggest you to get a bigger page and more like a spiral book's page... Something like that : http://static.ipsopresto.com/eCS/Store/fr_FR/up/imagesplus/IPFR4195_A1.jpg
That would add some personal touch to your page and to the wall too cause then the page start to be part of a book... So part of something bigger we can't see on the wall... Maybe you're a Trigun fan that only draw that anime in a fan's book! :p ^_^

Anyway HUM... Getting a little too far on the imagination side... Anyway... The writting on the top of the wall is good. But the circle around sexy should be the same color as the writing's color... As you probably wrote them with the same pen didn't you? :D

The "Trigun" sign is a little bof... Not really interesting... If you're a fan of the anime, you'll probably want to make it more flashy and "cool" looking...

For the text on the left side it's too regular and straigh to be real handwriting. I have so much troubles with those fonts that can't really give the "hand" feeling... You should make the writing looks a little more natural, nobody can't write as straight and especially if you don't use the lines! (that could also be of use to use the lines as real writing lines and write ON them and not between! :) )

Oh as you add some finance charges on why not add the classic coffee circle? :p

You can aslo give some credits to your wall by adding real looking things on like the cup of tea-coffee you are using while drawing, a pencil, an eraser,... But that's not really easy.

Note that you NEED to add your sign on a wall so nobody can steal it easily and it's a requirement for getting into the gallery...

Okay I guess this is enough stuff for today... Don't hesitate to send me a message if you need more information about my comments... I know I'm not always as clear as I would want... :)

Have fun!

I can say you that I like your "idea", your wall seems an "exercise-book" page with a sketch on it and I think this idea is preatty and actually original. So I think you should work to make it better without change its essence.

Is this any better?
Or should I simply stop attempting to make papers?

Background looks much better.

Still not digging the character having some simple filter done to him.

You shouldn't stop making wallpapers. It's very common to be very frustrated while making a wallpaper. Only thing you can do is keep playing with it until you've piled on hours of work. Even if the change is subtle, it will all add up in the end.

If you want to make a wallpaper, don't stop walling but don't think we gonna be telling you your wallpaper is good if we don't think so... :-s Here we can provide you advices and help so your wallpaper will be accepted in the Gallery.
If you just feel like doing a wallpaper for yourself, you probably don't need us...

Anyway about the wall,

The background is better indeed although I liked the color of the first version's background better.

As for the characters :
- You should really take of the scratched texture on your characters and focus on a more simple drawing style. Cause it's still looks bad the way it is. The change to grey is nice. It makes it like pen drawing but still too much texture.
- The red Trigun is not really needed.

About the text :
- The Trigun in red is fine.
- The text near the cat is OK.
- I miss the little handdrawed stars ^^
- The main text in the middle still don't feel handwritted. Why don't you writte it yourself and scan it? That would be unique! :p

Good luck