Start by breaking the problem down into smaller, more manageable parts:
Choose a platform. You mention using both C# for Windows Mobile and Java for Android. It's great to be open-minded, but pick one or the other for now. You'll have a hard time making much progress until you do.
Procure a development environment and test device suitable for developing on your chosen platform. Learn to use it. You don't want to be trying to learn the ins and outs of mobile development while also implementing your first computer vision project.
Build an app that can capture and process images from the camera. Don't worry about looking for words yet -- just get individual frames and do something very simple with them. You could display the average red, green, and blue values for the image, for example, or replace all the green pixels with pixels from a chosen image.
Learn something about computer vision and optical character recognition. I'm not up on how OCR is done these days, but I'd expect that some steps in the process might involve filtering the image to simplify it, doing some edge detection, and trying to match features of the resulting shapes to the set of known shapes that are the characters you're trying to detect.
Write some software that uses the knowledge you gained in step 4 to detect characters in sample images. Ideally, it should work for samples where the characters are distorted and the images include the kind of noise you'd get from a camera on a mobile device. You don't necessarily have to make this software a mobile application -- at this point you're just learning the techniques you'll need for your mobile app.
Incorporate the image processing software from step 5 into the app from step 3.
Note that steps 4 and 5 can (probably should) take place before steps 1-3, depending on your priorities.