Going to watch it - What to do first?

I disagree. I've only played the Dynasty Warriors games and I understood it all just fine.
It does a good job of setting up who characters are and what the stakes are. The only problem I foresee anyone having is that "all Chinese people look alike." But if you've gotten through Chinese movies before (Hero, Crouching Tiger) then you should be good.

I guess its kinda like watching Troy without reading The Illiad. Except that Red Cliff is awesome and Troy is only OK.


Some Academic Film Analysis
http://cinemaconfessions.wordpress.com/

Red Cliff is a version of core scenes from the great Chinese medieval novel "Romance of the Three Kingdoms". If you have read that, or seen the long Chinese TV series (available on youtube), then you will have some idea of who the characters are, and why the versions in Red Cliff are a lot better portrayed than in the TV series. Hence, that way you will get the fullest experience of this movie.

I'm on the second book of 4 of the three Kingdoms, I haven't reached this specific battle yet, reading the books basically just gives you more of an insight to the characters, saying that I think this movie has done very well to show what the charactors are truly like, such as Lui Bei being very humble and Zhang Fei being outspoken and very defensive. People complaining that this movie is too long have to appreciate this is one battle from so many and there are so many personalities to squeeze in.

Basically, the once mighty Han dynasty has reached a very low point due to widespread corruption and as a result civil war has broken out with rival warlords all claiming to be the true rulers of China. North of the river, Cao Cao has picked up the leading heir and rules in all but name. South of the river, Sun Quan is strong in the southeast and in the southwest rules Liu Bei, also a true but distant heir of the Han dynasty, now currently in the weakest of the three. Cao Cao has recently overcome all the rival warlords in the north and now seeks to reunite all of China by invading the south. The other two, who have fought in the past, are likely to unite in order to stop him.