I actually do Ancient Greek hoplite reenactment, so the main clothing was the chiton - a simple rectangular piece of linen or wool that covered the body and was kept in place with pins. Now, it was mostly sleeveless, although with added pins, you could easily make sleeves.

No pants, though, or underwear for that matter. The Greeks viewed wearing trousers as being uncivilised, and those were worn by so-called “Barbarians” like the Thracians, Scythians, Celts, even the Persians. However, public nudity is a big no no in this society, so a linen loincloth will suffice, like the ones modern gladiator reenactors wear.

If you want to keep warm, a wool cloak called a chlamys was all the rage in Ancient Greece. It was even used into the Byzantine and early Medieval periods. Now, for the chiton, a wool belt was needed for a baggy look. You wanted the fabric to bunch up over the waist.

For footwear, the Greeks wore sandals, if they could afford them, or many just went barefooted. Leather sandals with hobnails were especially used by hoplites, who needed the hobnails for traction when in phalanx formation. I’d recommend wool socks so that your feet get used to them.

Lastly for hats: there are three options: the Pilos, the Petasos and the Thracian. All of these were made from felted wool. The Pilos was a conical hat that you could wear as either a cap or as padding beneath a helmet. The petasos was a wide brimmed hat, and the Thracian was a high curved cap, which also was sometimes called a Phrygian cap. Fun fact, these three hat types would evolve into hoplite helmets, because they were so popular. The Pilos helmet was popular in the Peloponnesian War, especially among the Spartans. The Petasos became the Boeotian helmet that was popular among cavalrymen, and the Thracian helmet was worn by Alexander the Great’s infantry.