Partially copied from my answer in another thread:

The question of visual appearance of medieval soldiers is an interesting one. Medieval soldiers often equipped themselves personally, so their armor and weaponry would most likely reflect popular regional styles from where they lived. Uniforms were not issues, but there are some examples of early movement towards a uniform appearance for soldiers. English soldiers started using the red cross of St. George on their tunics as something of an "official" emblem in the 13th century (and possibly earlier). Kings and aristocrats, of course, had their own coats of arms: the famous fleur-de-lis on a field of blue for the French monarchs, the French arms quartered with three lions on a red field for the English crown. There are also some indications that particular regions might have had distinct colors for their soldiers. Archers from Cheshire in England are noted to have worn some kind of green and white pattern in at least one sources, but it's hard to definitively say that this was a universal or regular way of attiring soldiers.

In general, we can say that there were efforts made to make distinctions between soldiers for purposes of recognition on the battlefield, but given the nature of medieval military equipment, these efforts were never going to be universal or uniform in nature. It can be said with certainty that there would be more colors present on the medieval battlefield than what is usually depicted on television and in movies. Medieval people were not uniformly dressed in the muddy browns associated with them in media.

As for the "smartness" of medieval soldiers, the rigors of the campaign trail did not allow for any sort of parade ground pomp for the average warrior. The English archers at Agincourt are referred to in French sources as a rather ragged lot, with their breeches hanging down generally looking a mess. While we might attribute some of that to an understandable bias against them on the part of French writers, they were men who had spent months in a difficult siege and on a hungry, tired march through the French countryside. Replacing worn-out clothes or armor would have been difficult in such circumstances. Other sources also attest to the rigors of campaign life. Chaucer's Canterbury Tales describes the Knight's clothing as having been stained by his armor because he has recently come back to England from a foreign war. As soldiers today could attest, fighting in the field for a long period of time makes it hard to maintain peacetime standards of appearance.

Depends on the army. Chainmail, at least historical chainmail, had severalprice/quality ranges. Most modern reproductions fall into the cheapest one where the shirt is just a tube for body attached to two other tubes for the arms.

Then you have better chainmail grade, where sleeves are narrowing towards the wrists, or where sleeves have a bend in it at the elbow to assist arm mobility while wearing it.

At the top of the range is chainmail that is fitted rather precisely to the individual figure of the wearer. I know of exactly one reproduction of this that was still incomplete the last time I checked.

As for equipment as such, professional soldiers (so, knights and mercenaries mostly) took good care of it, so you'd only rarely see things like heavily rusted swords or armor, though it probably happened when they didn't have time for maintenance - a steel hauberk can rust really quickly if you have to walk with it in the rain.

Uniforms are another matter entirely, and MI13 already answered that, but there's one thing he forgot, the first faction that introduced actual uniforms as well as heavy professionalization to armies well before 1300 - crusader orders. Be it Templars, Teutons or Hospitallers, they all have standardized garb in their rule, determining what materials and colors they can use. That would give their units a fairly uniform appearance, though not 100% one to one, since their equipment was manufactured locally.

Last is weapon variety. The idea that all soldiers have the same weapon is not appropriate for a lot of periods in history, starting with the present day - those SAWs are menat to be used alongside assault and battle rifles, not to mention the occasional grenade launcher. Medieval weapon variety was similar to this - a shield wall with sword and shield guys in the first row, two handed axemen in the second row and spearmen in the third row definitely has advantages over just a block of spears.

Spearman behind swordsman in a shield wall (sword is relatively short, this configuration makes the wall less voulnerable to people charging up to it): http://manuscriptminiatures.com/4447/13997/ http://manuscriptminiatures.com/5195/16695/

Cavalry armed with a variety of weapons charging (not a great idea, perhaps their lances are already broken?): http://manuscriptminiatures.com/4154/12112/

Archers mixed into a shield and sword formation, probably to protect them from return fire: http://manuscriptminiatures.com/4186/8283/

Cavalry mop-up with everything in it (one dude is charging on a horse with, I shit you not, a dagger): http://manuscriptminiatures.com/4673/7954/