Sexing young birds

Lots of chicks, all various ages ( 1wk to 7 weeks), only ever hatched silkies and am quite good at sexing those if I do say so myself - hehe! Have no idea with these feathered blighters  I even managed to sex guinea fowl quite accurately  :blink:

I have cuckoo marans and speckled sussex, what do I watch for? I have cream legbars which are great could tell from hatching, however I have 2 legbar/skyler crosses and the one that was marked like a hen as a chick is a bit bigger that the supposed boy. And the boy looks hen shaped to me, could be because the supposed hen is crested.

So come on guys help me out, can you tell from the combs, their tails, spurs what?
Gona stick to silkies in the future 

You can sex them by looking at the wings, the depth, short ones are female I think!! or the other way around, i can never remember

Thanks guys, I will take photos of the legbar/skylers tomorrow and post them. Hopefully someone will be able to help