What is the best practice in blackberry development for reaching the widest range of smart phones?

I am wondering if anyone out there has experience writing application for blackberry smart phones. In particular, I am wondering how they get around the myriad permutations of model number/carrier and OS.

Is there a recommended approach on how to write your code so that it targets the widest range of smart phones?

Are there compiler switches that can be used to target code for particular model numbers?

Solution

Tips for wide range devices

The question is: how to write code that will handle different RIM OS, carriers and device models? In code that will depends on available/deprecated API, in workflow about handling carriers features and characteristics of device.

First of all, read How To - Develop applications for different BlackBerry Device Software versions and BlackBerry smartphone models

Wide range RIM OS support

StackOverflow - Which BlackBerry OS version to target for? - to be short, my choice is RIM OS 4.5

Tips for 4.7 - 4.6 - 4.5 - ? support:

navigation, use accelerometer and touchscreen, but don't forget about trackball and menu
borders, there are no BorderFactory in 4.5 and earlier
background, there are no Background in 4.5 and earlier
transparency, there is no Graphics.setGlobalAlpha(alpha) in 4.5 and earlier
multimedia, different formats are supported on differen OS and phones

Carrier support

I have no statistical information about BlackBerry carriers. But lets see what are those carrier features we can meet:

if we use carrier network resources, carrier controlls all network configuration. That means on ex. we may have no UDP, max. transfer file size about 3 Mb, and we will have to config APN settings
also, carrier and device combination defines what GPS type is accessible. And for Verizone, there is a special signing process to access GPS.

Different devices

Things which may help support set of devices:

use flexible, elastic UI elements, change size and layout according to screen size
use several graphic resources sets of different size
control font type and size
before use camera, check if it's available

Building several RIM OS

There are preprocessor directives, but I prefer to use BB Ant tools, copy/delete all platform version diff (code, resources) and target appropriate rapc directory from build task.