A roosters comb should start to get much larger and pinker than the hens. A rooster will also be bigger. He will start to get pointy and translucent feathers on his neck(hackle feathers) and the feathers inbetween his back and tail feathers(saddle feathers). His feet and legs normally be larger than the hens, and his tail will either take longer to come in and be ugly til he is mature(mine always had ugly and scraggly tail feathers until he started to crow and mate hens.) or it will be curved downward and have two feathers longer than the others. His back feathers will also start to get translucent. I saw that more in my two red roosters(one is a RIR and the other is a RIR x GLW) than my barred, blue, or gold birchen roosters, but I'm sure all 7 have translucent back feathers.
So yeah. I'm kind of new at this as well(only had chickens for 2 years) but those are some things I use to sex when they are older. As young chicks(two weeks to two months) I just look at comb development. I have a funny story. The first time I let my hen hatch chicks, I had been comparing combs like mad, trying to figure out which one was a rooster(because I was almost positive I would get at least one rooster from 5 eggs) but it turned out they were all hens.