Tempted as I am by the Android platform, one thing that I'm very reluctant to give up is auto-text. Before I got a BB, my Sidekick had auto-text, and I learned to take maximum advantage of it. I don't like to think about using a mobile device without auto-text.
Currently I have abbreviations for over 400 common words loaded into it. Some of them only save me one or two keystrokes, but I've found that when it comes to words that you use all the time, the saved keystrokes add up and result in much faster text entry. I have "bcm" for "become" and "wtt" for "want to" and "hvt" for "have to" and "intg" for "interesting" and on and on. I still add entries, but at a slower rate than when I first started. In essence, I use auto-text as a personal shorthand that I can set up exactly as I want. In my opinion, predictive text pales in comparison.
I know that some people don't bother much with auto-text, and just leave it with the default corrections of common misspellings, or even turn it off. I'm curious to know whether many others use auto-text the same way, and to the same extent (or more) that I do.
I think many people use auto-text for long words. I live in Philadelphia, and you can be sure I have an abbreviation for that. But the real key is to use it for common words and phrases. You can get English word frequency lists online, but you really just need a little reflection. And if you add a few at a time, you learn them very quickly.
Many of my abbreviations just leave out the vowels. I have "gng" for "going" and "gngt" for "going to"; "dn" for "done"; "wlk" for "walk" and "wlkg" for "walking", and so on. Even though "wlk" only saves me one keystroke, it's a common ("cmn") word ("wrd").
Remember to add all the grammatical variations. If you use "nd" for "need" then you'll need "needs", "needed", and "needing" (nds, ndd, ndg, in my case). And since "need to" is a commonly used phrase, I also have "ndt", "ndst", "nddt", and "ndgt". At first glance this all looks like gibberish, but if you do it thoughtfully and systematically it's just amazing what you can do. In fact, I find myself wishing I had auto-text on my regular computer.