Wow that's fairly quick (I actually procrastinated until mid march before I annotated anything ahhaaha) but it's still a good start.

Before actually memorising and gathering quotes I would suggest that you think about these aspects of the book (this can be applied to any text):
1) themes (think about the holistic themes, and also themes that are raised at certain sections of Medea)
2) views, values and authorial intent (the Ancient Greek male perspective is very important here)
3) audience (what sort of emotions are evoked when a character says something, etc)
4) language (Medea is FILLED with language patterns and literary techniques, and if you can identify these techniques you can easily enhance quality of your essays)
5) characters (this is fairly obvious I guess, also try to identify the gap between male and female perceptions on society based on Medea's characters)
From that you can perhaps try to plan a few essays, or write some if you want to (open book), and by doing that constantly you'll realise that there are a lot of quotes that can be used frequently on almost every essay you write (these will be the important ones you memorise). This will save you heaps of time to do any deeper study on Medea.
More things to add:
Also think about the social, cultural, ethical, and historical implications of every decision made within the text itself, that'll help. If you have any questions just send me a message I'll be more than happy to help.
