Lately I have been focused on a fighting kit for a paladin character, but what would a paladin wear outside of battle? I've been pondering this and have been researching kit from the crusader military orders. Here is a particularly useful site on Templar kit - The Noble Company and Order of St Maurice.
I've found quite a bit of useful items at Medieval Collectibles:
A plain linen coif
Topped by a beanie-style cap.
Round caps are also appropriate, but I think most people will associate the beanie with a religious figure.
I could also use a nice hooded cloak. It is available in cream.
I toyed with the idea of getting a proper monastic robe, but I think my tunic is fine. I could use another plus more tights.