tida

Hi, I actually like the concept of your wallpaper.

However, for now, to make it looks better, these are my suggestions:
1. Concept. Put the male and female faces on the back, while the scan where they're hugging in the front. Note: make the faces less seen by reducing the opacity.
2. Male and Female faces on the back. I think you should try to find a nice scan with the same pose so you can make a great wallpaper. Try making them less blurry, especially some parts which you can see is extremely blurred or sharpened, which maybe because you resized them from a small screen shots into as big as wallpaper. Are those screen shots? if they are, not good, because you need to paint or vector them.
3. Text. I do think the color of the text need to be changed. Because you can see, nothing on the wallpaper is pink beside the text (well that usually not a problem, but I think it is this time). So you may want to change it to other color. And what I usually do, I choose random color and experimenting with the blending mode in photoshop until I think they look nice.
Oh, and trying new font will be really nice. Try take a look at Dafont for some nice fonts.
I think it will be better if you actually put it on the center, but that is only to me though, because your tida here usually has weird tastes, LOL.
4. Others. For some romantic feelings you want to have (yes? or no?) you can make those by adding some blurred round shapes with different sizes on the front. That will be really nice. ;D
I think that's it for now. Maybe I can give more thorough critiques later.

May I know what program do you use? if you use photoshop, maybe I can help you explaining to you step by step to achieve some effects to make the wallpaper looks better.
I'm sorry if I'm not really clear with my comment above, but if you have some parts that you don't understand, or want some helps, feel free to ask. ;D
I hope my comment can help you a bit.

dylkim

The extraction is impressive and it's a good centerpiece.
...but the idea isn't succeeding. A common mistake I see is when people build their color schemes off of something that should be kept unique.
In this case, it would be Luffy's shorts. If you take a moment, you'll notice that the background is too similarly colored (and even richer) and actually takes away the boldness of the shorts that would otherwise pop in a differently colored BG.

The lines match with the men in black but straight horizontal lines are very boring imo. You might try slanting (slightly?) them at weird, uneven angles (think Donkey Kong arcade) and perhaps varying their thickness. The line at Zolo's neck should be brought down to the top of "One Piece" and then should be slanted south-east to the bottom right corner, for example. This would open the space above the line greatly, but see my idea below.

As for the spaces in between, this is where your creativity comes in. However, this is the first thing that popped into my head:
Blue is a complementary color of orange. My idea would be to get a big blue sky with nice clouds and stick em in one of the spaces. I would suggest moving scan so that Luffy gets the focal point that the sky accentuates.

Lastly, "One Piece" needs a bit of amping up because compared to the scan, it looks slightly dried out. Maybe vector this and ensure the whiteness pops.

As for your signature, put it into a big, fat, bolded font and make it black. Then position it so that it appears to be rising from the bottom black border.
Just a suggestion but try it if you don't know what it'll look like...

There's so much you can do with this and those are only the first things I thought of so take it all for what it's worth.

clarings

I don't agree at all...
the sky looks fine.. and the outlines thickness is ok.. they are from the original scan.. so there is not much that you can do about it.. besides the thickness is not meant to be constant.. even in vectors it changes..

Ok back to the wall..
the grass looks much better... fix a little the right side..
and the lines are still too noticable.. maybe it could look better if you try adding more lines of grass... to make it more filled (but try not to make it look scratched)
get rid of the japanesse text on the right-top corner...

and again the title is not right >_<
why don't you try cutting it... like this...
Journey to
a New horizon

and you could get rid of the star thing at the back.. and just play with the colors of the text... change fonts, and try glowing effects..
goodluck!!