If you work with other languages in addition to Python, it's easy to fall back into old habits. You should internalize the content from these two excellent presentations:
Raymond Hettinger's "Transforming Code into Beautiful, Idiomatic Python":
http://pyvideo.org/video/1780/transforming-code-into-beautif...
(pyvideo.org has a lot of other great talks and presentations.)
Ned Batchelder's "Loop Like A Native":
http://nedbatchelder.com/text/iter.html
Python Module of the Week is also an excellent resource: