while not the only way of doing things, or even my own only way of doing things, here is my demonstration (for a friend....and whoever else is interested).
I used Afterlight for both of these images.
I took this picture with my ipod 5. Same camera as the iphone 4. Set the page on a white board right next to my big window. you can tell the right side of the page has more light than the left but I'm good with it. I try to hold it right over the center so the corners are all square.
in the app: rotated and cropped to a square.
next I added contrast (the half black half white circle) using the slider.
then added brightness (the sun). as much as I thought the picture could handle.
then applied a filter. in original filters I used Lume. I always choose this one for paper stuff like this. this filter adds a little more brightness also. 
next sharpen. it is a slider, the one all the way to the right that looks like triangles. sharpened all the way to 100. it makes the details come out better and makes everything appear clearer. take the picture as focused as you can, but then always sharpen it.
here's another. the original picture. I know it seems dark but I would rather catch the details and then be able to edit it brighter than take it overexposed to begin with.
next cropped it to a square since I like all my mobile photos like that. here's an example of cropping that bugs me. I always try to keep the main part of the picture and get rid of whatever else I can that distracts from it.
that's much better to me.
this time I used the exposure slider. it looks like a plus and minus in a box. you just go up until you start to lose details in the bright parts, then scale back a tiny bit.
then add brightness. my love. I know that most of the filters I like increase brightness a bit so I won't overdo it in this step.
then a filter. I tend to use Breeze, Goldfinch, Olive, Marine or Coral. and never very much on the slider. usually 30 or less.
every picture can benefit from some amount of sharpening. so do that always.
then at the end (and after it's saved) is when I would add a shape like this.
I do know PicTapGo is another super one for good looking editing. when it first came out it stripped the exif data off of pictures so I never got used to using it. most people would probably not care about this :) The exif data has all the information about when a photo was taken and I used it to organize all my pictures from all my cameras by date. one of the updates since then though, has fixed this. it will probably become one I use a lot more once I get the hang of it and figure out what I like.
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