Hey! Don't worry, that feeling of being overwhelmed is intentional; I have no idea why the BoS thinks that giving 18 year olds a text like Hamlet, which is perhaps one of the most critically acclaimed and analysed texts in history, is a good idea... Look at all the notable critics on Hamlet if you need proof.
If you're looking to write your essay scene based, then really just look at any of the characters' soliloquies, obviously Hamlet's most importantly. They are actually all equally important as the other because they epitomise the key themes and characters' progression in each Act of the play. I don't think doing your essay scene-based is a good idea, the play itself is a lot more complex to do it that way, which I think will largely undermine the significance of the play overall.
I suggest doing your play conceptually/thematically. I focussed on corruption, delay/resistance, and ultimately why Hamlet has an irresolution (essentially the fact that the ending to Hamlet is retarded and unsupported by what happens in the entire body). Doing your essay thematically allows you flexibility with choosing the best quotes from
all the different parts of the play (which is something the BoS has started cracking down because too many people only quote from one section of the play). In that way, you can analyse how a theme has arisen, its progression as events occur, and how it's been resolved in the conclusion (or poorly resolved as I did it). Maybe the bedroom scene in Act 3 I think, Ophelia's funeral, obviously the "get to a nunnery" scene, are some of the more important ones off the top of my head, but it really depends on what you intend to explore in your essay.
Not to be a solid sell out or anything, but I have some resources that you might find useful for Hamlet, including a few essays and a powerpoint that might help
You can find my thread on the buy/sell forums if you're interested.