Methods of chick sexing

The two main methods of sexing chicks: feather sexing and vent sexing.
Feather Sexing
Feather sexing isn't hard, but it requires that the chickens be bred to show their sex in differences in the feathers as chicks. Male chickens in these breeds have longer wing pinfeathers than the females do, which makes them relatively easy to tell apart. Most chickens do not have these traits bred into them, and the chicks are identical to all but the skilled eye of the pro- chicken sexer.
Accurate Sexing Methods (Chickens)

Sex-Link Color
: A sex-linked chicken is one who's gender can be easily determined at hatching due to males and females being different colors. Without any genetic mutations, we can expect the following to be true:

Barred hen + non-barred rooster = Barred males and Non-Barred females
Gold hen + silver rooster = Silver males and Gold females
Barred rock hen + Rhode Island Red or New Hampshire Red rooster = Black with white spot on head male and solid black female (this is a Black Sex Link or Black Star)

Those are just a few examples of the various sex-linked combinations.

Vent Sexing
Vent sexing is performed by examining a day old chick's vent for the presence, or lack of, the formation of a male sex organ. The chick is held upside down to perform the examination. "Experts" are 95%+ accurate at this method. "Non professionals," after being taught the basics of vent sexing, can easily achieve an accuracy of 60-70%.

Watch them grow
The easiest but longest way to tell sex is to simply watch your chickens grow. In males, look for a larger comb, shinier, more pointed tail feathers (unless the breed is "hen feathered") and crowing. Females generally have smaller combs, tail feathers that are more rounded on the ends and, of course, they lay eggs.