help a fan out, guys

The second series of The 100 started here last night; I watched the first two episodes of the first series before giving it up because I couldn't tell any of the young male actors apart. But it has a good buzz from all you people, so I gave it another shot. It seems interesting but I STILL can't tell any of the younger male characters apart. They all have the same hair, and their faces are covered in blood and dirt! I was at one point trying to use "how much dirt and blood" to figure out which was which; it helped a little but not too much because I still don't know who they all are. Is there some kind of handy guide? What do I need to know to keep watching?

Also, the people in the radiation shelter: cannibals, surely? (This is a word Spartacus has learned recently, because of his interest in crocodilians, except that he says "hannibal" instead, and I don't have the heart to correct him.)