I recommend doing a 3/4. If you are reasonably organised and good with time management I would even recommend doing 2 3/4s if your school will let you. It will definitely alleviate the stress in Year 12.
Subjects I'd recommend
Psychology 3/4: Definitions are key. A lot of content. Some parts are incredibly boring (States of consciousness) and some parts are very interesting (sleep, memory..) - based on my personal experience

Biology 3/4: I really like it. Conceptually more difficult than psychology. Less rote learning and definitions to memorise.
Health Human development (3/4): Never done, (i've heard that theres a lot of content) Usually people who take either really like it or hate it.
Geography (3/4): Never done it before. You get to bring in coloured pencils into the exam

You get to cover environmental issues etc.. If you enjoyed humanities in Year 10, you'll probably like Geo.
These subjects can be content heavy but isn't really difficult. The score you get at the end of the year is proportionate to the time and effort invested into these subjects
Further 3/4 - I don't do this subject but I've heard people say that it doesn't require a lot of work, and there isn't a lot of content.
Very easy if you are having no troubles with math. You just need to be very good with accuracy. If you are aiming high (45+) you need to ensure you don't make too many mistakes. That's the thing with VCE math and (chem/ physics) in general, you can know absolutely everything in great detail but if you make careless errors on exam day you can't be expecting to get a good score. Careless errors are harder to make in content based subjects, but I reckon do require lot more effort and time to hit the really high scores.
Business 3/4: (I'm not sure if you can do it without 1/2)
People say it's a very crammable, easy subject. You can seriously do well by ROTE learning the content.
lol.