This is a very nice hoplite figure, from accuracy point of view. All pieces of equipment fit together nicely for Persian wars - Ist half of 5th century BC period. One slight correction - you could try to make spearhead much slimmer.
Shield could be painted, stay in polished bronze or polished bronze with centre device and edge painted. It could be also have some images painted on the inside.
Helmet can be polished bronze or painted for ex red, black. It can also have edges finished in colour or even painted chequerboard pattern. It can also have animals or mythical creatures on the sides. The most expensive option, if you want very rich hoplite, is silvered decoration on bronze.
Crest should be in natural colour, check the colours of horses (crests were commonly made from horse tails).
Armour should have generally geometric designs, coloured edges etc. On shoulder pads common were: multi rayed stars (like on boxart) and Zeus's thunders (you can see half of it
here, on famous Alexander's image, it was symmetrical)
Colours you should stay away from:
dark, blackish blue
dark, backish or purplish red
those two colours are approximations of tyrian purple (described as colour of clotted blood), generally too expensive for majority of hoplites (even those richer, like the one in figure you have). This dye was produced in Tyre, Phoenicia, and majority of production went to Persia.
On the other hand some purples, less saturated were more affordable.
deep yellow-orange - this is saffron, again very expensive dye produced in Persia
You may try to find inspiration in ancient Greek pottery, for example type names of famous heroes like Achilles, Hector in the picture search
or use some archive, like Beazley Database
http://www.beazley.ox.ac.uk/xdb/ASP/testSearch.asp?searchBy=Subject
And especially:
http://www.beazley.ox.ac.uk/xdb/ASP/testSearch.asp?searchBy=Subject&decorationHeading=Warriors&forceSearch=true&additionalSearch=Warriors
Here, you will find shield devices from pottery gathered in period groups
http://www.ne.jp/asahi/luke/ueda-sarson/Greek_shield_patterns_1.html
You can also try to find pictures of Greek coins and copy on the shield image from those.
Hope this helps,