WE can't avoid any flaws in the new films, save from avoiding the films themselves. Only JJ and his crew can do that.

I'm going to buck the trend and say what was right about the prequels: It re-framed the story of Star Wars as the tragedy and redemption of Anakin Skywalker, thus making them somewhat relevant, in theory if not in reality.

One danger of episodes 7-9 would be to focus on the story of Luke, or (god forbid) Anakin. The story should be re-framed to be about the Skywalker family as a whole, with a focus on the younger generation. Not to say that they shouldn't play a part, but they should never distract from the new leads. Of course Luke should return as an Obi-wan mentor type, and I'd even be open to Anakin's ghost returning at the end of the entire "tri-trilogy" and doing some great feat through the Force to truly atone for his past actions and allow him peace. But keep them to peripheral characters.

Another potential pitfall is the overuse of CG. Take the actors to genuine locations and sets, allow them a realistic world that they can interact with and believe in and I will believe in the world with them. I don't think that JJ intends to skimp on the practical effects, but paradoxically this space opera is best when it's effects are down-to-earth.