Reading points: some matters to consider as you read:

Psychological realism in the portrayal of Beatrice and Benedick, particularly in how they change or evolve over the course of the play.

Much Ado as a "comedy of character" as opposed to a comedy of circumstance (as in A Midsummer Night's Dream, e.g.).

Dramatic irony, where the audience's knowledge is greater than the characters' knowledge, and again, illusion in conflict with reality: error or misperception vs. intentional deception.

Don John as a comedic villain: compare and contrast with the tragic villain, Iago.

Points of intersection where the two love plots echo, mirror, or otherwise interact or comment upon one another.
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More specifically in comparing the two love plots: one as melodrama, the other as commentary on conventional romance.

Naturally, Shakespeare's commentary on the nature of love.

 Thematic functions or ramifications of the humorous Dogberry and crew: why is Dogberry even in this play?  What does he contribute?

 The interplay of tragic and comedic elements (or potential) throughout the play.

Shakespeare's commentary upon women through Beatrice and Hero.

Places where the play may seem a bit disturbing to the audience.

Points of connection between Much Ado and the three earlier comedies we've read (or the histories or tragedies, for that matter).

 Shakespeare's portrayal of violence in verbal sparring between lovers.

 Shakespeare's commentary on gender or gender roles: characters both conforming to and defying their typical gender expectations.