How to prepare a Journal Club (or Methods) presentation?
(this is rather long: I wrote it for one of my students, who had a similar question)

BASIC UNDERSTANDING
When you're processing a paper, ask yourself:  


what is their precise problem formulation
what is their solution
what larger issue are they trying to address with their paper
Do (1) and (2) actually fix (3)
(for experimental papers) do the experiments tell a convincing story to bolster their claims. Be suspicious of what they claim unless the line of reasoning is clear. 


SYNTHESIS
Once you've done this for a set of papers, you should start trying to connect them together:


is there a linear progression of ideas ?
How do the tools connect up
Is there some way to simplify and explain what groups of papers are doing under a common theme ?


CRITIQUE
Once you have the above, then you can ask    


what are the gaps in what people are doing        
Are these gaps important or minor ?
Does some union of the papers essentially solve the problem ? if so, why and if not, why not ?
Are these papers even solving the right problem ? (this last point is both tricky and critical - it is very easy for a line of research to be internally consistent but get totally derailed from the original motivation for the problem)


DIRECTIONS

Now you're ready to suggest new directions and new ideas.

note that critique comes AFTER basics and synthesis - you must understand very well before you can judge.