Little late but hopefully I can be of some help as I did these two units last year and got 96 (Odyssey) and 100 (Tragedy) UMS. For Tragedy I studied Antigone, Agamemnon, Electra and Medea.
First off, for each text its so important to have a firm understanding of plot, otherwise you'll throw away the 10 mark questions that actually super easy.
For my Odyssey I did very little revision after I felt I knew the plot inside out. This is what you should spend most of your time on in my opinion because all character and theme questions become really quite easy once you have the plot down. As you go through the plot also make note of interesting character actions, similies and omens to help with essay questions. After this I just made large mindmaps on themes in the epic: xenia, kleos/time, identity and disguise, oikos/nostoi, gods, women, slaves, fantasy versus reality, and omens/prophecies. Try to make these as detailed as possible, using a number of examples for the characters you apply the ideas to.
For Greek Tragedy I revised using:
-Relatively detailed summaries of each play, pulling out short quotes for certain characters. Don't get caught up in this as my teacher stressed that you can get an A* without quotes (obviously not in extract questions) and I don't recall using very many
-Overview of the structure of each play (prologue, parados, stasimon, exodus, kommos etc.). This isn't necessary but it will seem impressive in the exam if you can throw out some of this terminology...
-Character analysis for protagonists in each play (e.g. Antigone with loyalty to family, loyalty to gods, and empowerment/femininity)
-Mindmaps on moral condemnation of protagonists (villainous or victims/virtuous) - this has featured so many times in exams
-How dramatic irony features in each play (handy for a 'dramatic/interesting passage' mini-essay Q)
-Mindmaps on themes for each play: power, women and society, morality, fate and freewill, justice etc.
-How tragic terminology applies to the plays and their protagonists: peripeteia, anagnorisis, agon, hubris, hamartia, catharsis and messenger speeches - this is especially important and basically must be discussed to get good marks!
Good luck and don't stress, with a subject as subjective as classics there's only so much revision you can do and if you have a solid grasp of plot/character you'll be fine.PS I think I still have the majority of my revision notes so I'd been happy to send them to you if you end up struggling.