Taking Suitable Photos with an iPhone and little Vision

Hi there, I'm virtually blind, but want to make use of photo-based apps such as Cardmunch (to scan business cards) and oMoby. Can anyone suggest any general guidelines I might use to take pictures these apps will recognize? Any attempts made so far are "too dark" or "too blurry" for adequate recognition. Any help you can give is greatly appreciated. Thank you.

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#1 info on OS and Phone Mondel

BTW, I'm using an iPhone 4S running iOS 5.0 and VoiceOver.

#2 Here is a useful product for just that!

Weblink: http://www.kickstarter.com/projects/limemouse/scanbox-turn-your-smartphone-into-a-portable-scann