How do anda make a bad quality picture look better?

I do my crossovers on pixlr, so I create a new tab and then use paint to paint over bad quality areas with the corresponding color. That's what I do for most of my Tarandy pics, like link one. That's all I know, besides using effects to cover up bad areas.

I usually cover it up with effects, slight blur then sharpen. I use fotoflexer.com to cut the picture and put it where I want the cut images. On fotoflexer there is a beauty tool that allows me to soften and sharpen. That usually helps with poor quality screencaps. Then I save it and use pixlr.com/express/ and crop and ubah it. Usually the effects cover it up and if not then I use a blur set on 1 and then sharpen it. Hope that helps. That's what I do. The below picture was made with poor quality screencaps. (Don't know if that helps atau not.)

I always try to make my crossovers look good without adding to much effects.. i kinda don´t like that and it´s a challenge to do it without them, which i like Xd

If the edges are to blurry i sometimes draw a bit over them, with a soft brush.. i color-correct a lot...
It´s hard to explain, because i use several things to get my quality done :)

First I started with this image and then I added a simple effect, that's all and got this:link

I do not know.