The most basic hair style was a bun on the back of the head, with about half of the woman's hair. The hair in the front was left unbound, pinned up, or wrapped around a rope like the video of the hairstyle of the Vestal Virgins shows. This was seen as either an alternative, or an additive, to veiling. While I veil on rare occasions in ritual, wearing my hair up has become a staple of my life and I rarely--if ever--go out with my hair completely unbound. During Hellenic times, women often waved and curled their hair, but parts of it were still restrained.
Short haircuts were functional for servants and slaves who had to work during the day, making long hair the privilege of wealthy citizens. Female warriors and athletes, especially in Sparta, cut their hair short as well, and within Spartan wedding ceremonies, brides had their heads shaved. During funeral rites, women wore their hair down, and tore at it to show their grief. As a sign of grief, the hair was then sometimes cut.
Hellenic women often had dark brown or black hair, but the beauty standard was blond. Both men and women bleached their hair, as well as drying it in the sun to reach a lighter color. In the Odysseia, Odysseus is described as being gifted blond hair by Athena:
"And when he had washed all over, and rubbed himself with oil, and put on the clothes the virgin girl had given him, Athene, daughter of Zeus, made him seem taller and stronger, and made the locks of his hair spring up thickly like hyacinth petals. As a clever craftsman, taught his art by Hēphaistos and Pallas Athene, overlays silver with gold to produce a graceful finish, so the goddess graced his head and shoulders. Then he went some way off and sat on the shore, alight with that grace and beauty: and the girl gazed at him admiringly"
Young boys cut hair short--to about chin-length--when they reached adolescence, and kept it that way until they became older and more distinguished. After that, men tended to keep their hair long in Athens. In Sparta, young boys' heads were shaven, and the men kept their hair short. For a long time, ancient Hellenic men wore beards. It was Alexander the Great who ordered his soldiers to cut off their beards, so the enemy couldn't grab on to it in battle. After that, the beard became a scholar's prerogative. Most men who were not in the army indeed had beards; they were a mark of distinction and virility.
There were several popular ancient Hellenic hairstyles: with a krobylon the hair is gathered, tied and pinned over the forehead; the kepos is a bowl-cut used for youths and slaves; the theseid is a sort of proto-mullet which was short in front and long in the back; and with the hectorean, the hair was combed back into curls.
Within a religious framework, hair was done up as well, unless otherwise specified. Many Dionysian rites, for example, encouraged women to literally 'let their hair down', and join in the revelry. For (married) women, it was extremely uncommon to wear their hair down outside of the oikos, and to do so must have helped them get out of their comfort zone. For other religious ceremonies, wearing the hair up was a way to apply katharmos, and prevent miasma from entering the ritual setting. This is a practice is still applied today, by yours truly included.
Interestingly enough, this is one of the ways in which the outside world can see my transformation into Hellenismos; before, I almost always wore my hair loose. I'd been experimenting with a shorter hairdo prior to my progression. Now, I'm growing my hair long again, and only wear it down inside the home. Yesterday, a visitor came to the door just after I'd showered and dressed; my hair was still down. I felt physically uncomfortable that a stranger saw me with my hair down, and put it up in a loose knot as soon as I could. It's a sign of devotion and purity for me, plus, there is something beautiful about only letting your partner see your hair undone.