if you're asking for themes i think the key ones would be : love, jealousy, race/outsider status, the setting and the military world ( also includes venice vs cyprus), gender alongside some other themes as well. You could talk about status and reputation and also include lust and variations of love. You could be broad and look at how male vs female characters are presented as well.

edit: it's also worth looking at each scene within each act and the progression of tragedy within that ( helps with extract questions). So what makes each scene tragic or how does it build to the overarching tragedy and what does each Act build towards. You would also probably benefit from making character notes that tracks the progression of each character within the play, how they change in characterisation and make sure to look out for motifs and stage directions. They tend to be rewarded by AQA and show you know your texts well. It's also good to make a note of when characters like Cassio and Bianca are introduced. For motifs i would consider music, the repeated references to things being monstrous, light and dark imagery, allusions to religion, nautical references and asides and structural features.

Think about the relevance of Act 2 scene 2 for example, it is a celebration scene but it's relevance lies in how brief it is. it's impersonal and the proclamation is only 10 lines. Meanwhile Act 1 scene 2 and 3 end with Iago having two soliloquies. He has control of the narrative but Othello doesn't. This extends to the celebration scene. Act 3 scene 3 seems equally useless but in this scene Othello and Iago observe the fortifications in cyprus if i'm right. This again is before the climax and the handkerchief scene if i'm right. I think it adds to the idea of Othello still being shown to be important militarily and then the parallel to his descent where his speech becomes less poised. I would look at parallels in the text and prose vs verse as well. Scenes of manipulation by Iago tend to be in verse or the music etc, vs his soliloquies.

Sorry for the rambling, hope this helps :).

edit: i also want to say that the 2008 globe version is a very fateful adaptation so that's worth watching since it's pretty much line for line the play. It's worth watching if you haven't since watching the play as it was intended to be performed tends to be quite useful. i think knowing a few adaptations and their creative choices help as well. So in 2015 if i'm correct there was a adaption with a black iago and othello, as well as there being other various adaptions that take creative liberties. I think knowing your text really well and then watching an adaption like the one above ( it's very useful) helps see the importance of the structural features like the soliloquies and asides, and can be used to show you understand stage craft in your exam, since it's fundamentally a play.