In addition to Jeff's response I try to use links to prexisting questions in comments to nudge people in the right direction. 

For example I got sick of asking people for debugging information in every comment so I made a question and now just leave a comment and link them here: https://askubuntu.com/questions/14008/i-have-a-hardware-detection-problem-what-logs-do-i-need-to-look-into

Also, as a whole we could all do a better job going back into old answers and cleaning up (deleting) old comments that made sense while trying to work out the problem with the person and instead now just clutter and confuse the answer.