I've found success by focusing on the appearance of sincerity of what I say. The other key insight was making sure that I was spending time trying to figure out what the other person is actually proud of, instead of what I was most interested in.
In other words, don't worry on originality - focus on saying something positive about the thing the other person is interested in.
I suggested recently that part of the problem with with LW was a lock of discussion posts which was caused by people not thinking of much to post about.
When I ask myself "what might be a good topic for a post?", my mind goes blank, but surely not everything that's worth saying that's related to rationality has been said.
So, is there something at the back of your mind which might be interesting? A topic which got some discussion in an open thread that could be worth pursuing?
If you've found anything which helps you generate useable ideas, please comment about it-- or possibly write a post on the subject.