I recommend starting with AMOS Professional. It's the best version of AMOS so far. The interface is better than in previous versions, the help-function is working fine and there's a ton of extensions (adds new commands) available for download.

I strongly recommend getting the AMCAF-extension from Chris Hodges right away. You can find it here:
AMCAF downloadI've written a short article about the AMCAF-extensions and the Easylife-extension on my blog. Feel free to check it out here:
Review of AMCAFAs mentioned by others, AMOS Professional works fine on the Amiga 1200 with a HD.

You can find the manual for AMOS Professional here:
AMOS Professional manualHope this was of help and best of luck with your programming!
