1. The Eclipse plugin makes life much easier so use it. If you are used to Intellij IDEA then try out the Intellij IDEA keymap for Eclipse
2. Some information about signing keys:
   • You don't have to get signing keys to make a deployable application
   • They are inexpensive
   • If you do get the signing keys you will have access to libraries that you otherwise can't use
   • You will need the JDE installed even if you have the Eclipse plugin installed as explained here
3. When sending apps to the background:
   • Make sure you don't exit() the app, only call Application.requestBackground()
   • Make sure to provide an exit menu option
4. Install the MDS emulator. You need the MDS emulator if you plan to do anything that requires a network connection.
5. If you need SOAP support use kSOAP. There is a good DDJ article with examples on how to use kSOAP in a mobile setting.
6. Use Display.getWidth() to make your custom items look correct on any device. Keep the following in mind:
   • Make any static graphics you use that need to span an entire screen as large as the largest device size
   • I have created a list of BlackBerry device screen sizes
7. The BlackBerry has an embeddable browser. There is a good example post on how to use it.
8. Spend time to make a splash screen. The knowledge base has a good article on making a splash screen.
9. Make good looking icons and make sure to also define the rollover icon.
10. If you need charts in your application take advantage of the device always being connected to the internet and give Google Charts a try.

This data comes from the BlackBerry devices page.