I don't have a scanner. How can I clean up a photo of a piece of paper?

Recently I've been asked to print a piece of paper, sign it, scan it and then send it back via email. Unfortunately I don't own a scanner. I'm hoping I can take a photo of the paper and then manipulate it in Photoshop so that it looks similar to the output of a scanner. So far, I've taken the image, used the Perspective Crop Tool to straighten it and then rotated it - but now I need to try and get the text crisp and clear and the colour of the paper as white as possible. At the moment it has a slight blueish tinge from the top left hand corner. Can anyone advise on what I need to do? I tried c

Question by Richard on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.