Most Greek helmets will look like the Italic Corinthian design, which is characterized by a tall plume that may be made into a pony tail at the end. It also has the long cheek guards with a slot in the middle for maximum air flow. It also will be a tan plume, red, or black. Depending on the color of the rest of your outfit (black, brass, or bronze armor), any of these plume colors will do. The most popular out their for the Italic Corinthian is going to be the tan and red plumes.
Another popular Greek helmet is the Hoplite helmet. The Hoplite was a common soldier for the Greek armor and they carried the recognizable white round shield and a long spear. They were excellent for repelling cavalry and charges by soldiers. However, being not very maneuverable, they were vulnerable to attacks in the rear. The hoplite helmet usually has a tan or whitish color plume. Often times it was made into a braided pony tail at the end of the plume.
The main thing to remember when looking at Greek helmets is that many of them look very similar. This is most likely a good thing when you are doing your historical research or are looking for a helmet to purchase. Even if you accidently buy a helmet that is not quite historically accurate, your helmet will look similar enough to the others that the general populace will not know the difference.
