Most things work for some breeds but not for others. Cross breeds get tricky, but here's my list:
1) Pullet tails often come in earlier, and cockerels tails and wings tend to have more down. This only works in the first two weeks.
2) A bird with a distinct stripe on its head is likely to be a pullet. A chick with no stripe is often a cockerel. Again, this only works for about the first week, and the indistinct half-stripe could be either.
3) Lay the chick on its back. Note that ALL chicks will struggle initially, but the girls will settle quickly and the boys will fight to turn over. This has to be done within 24 hours of hatch.
4) If one of your chicks has a distinct white "cap" at the shoulder, it's likely a boy. Unfortunately those without the cap could be either.
5) Wing sexing can be a little trickier, and I'm not good at it yet.
6) Behavior. Even as day olds, many (not all) cockerels will stand straighter and be more alert. They may also be more protective.
