Overcoming nerves from anticipating conference questions
There are a few obvious questions to ask yourself in planning for questions:


What are the inherent weaknesses in the current work? (Almost no research is completely "airtight," so figuring out where the weak spots are will make a difference.)
What are the ramifications of whatever assumptions I have made? Are they logical? What happens if I strengthen, relax, or eliminate some of those assumptions? Will everything still work in the more general (or more restricted) case?
How would I apply this work to other problems? How will it help others in the field?


And then, with respect to the presentation:


Have I left anything out in the interests of time that would potentially interest the user? Is the research methodology clear? 


If there's anything in the last point, you may want to plan on having additional "backup" slides which highlight that info, but that aren't part of the "main" talk.