After reading this question, I started to think about how clothing would affect magic in my setting. Just like in Incognito's world, the basis of magical abilities, Enchantments, and spellcasting is absorbing mana (magical energy). Absorbed mana is then harnessed to cause an effect.
However, clothing in my setting does not necessarily impair mana absorption. Enchanted materials (like monster drops) act like circuits, drawing energy from the environment to power their function.
Thus at first glance it appears most magical clothing will divert power away from the mage wearing it, and possibly even create interference (gargoyle leather=Earth magic, which does not play nicely with Water magic...). However, as time goes on, mages become capable of not only absorbing pure, ambient mana but gain the ability to imbibe and utilize mana from monsters and other magical creatures.
However, then someone hits the hurdle of 'magical influence;' if a fashion-loving Water Shaman decides to wear a bikini of red dragonhide (because it'll go with her blue eyes and hair) her outfit will A) generate small amounts of Fire Magic, warming her while also attracting ambient Fire Magic and B) if used as a power source, will make her Water spells more than a little heated.
This means that if someone casts Fireball at her, it'll be more likely to hit, much like someone's more likely to get shot when they have a supermagnet inside their stomach and everyone around them are firing steel-coated bullets. It also means that her Water spells may inadvertently cause reactions in heat-sensitive items when powered by her outfit.
So, it'd be better to just wear clothing made of one's hair or something, right? Actually, no, that has problems of it's own! Precisely because clothing of that nature comes from one's body, it actually draws from the wearer's own mana reserves to repair and protect itself. Thus such clothing actually drains one's mana constantly!
However, then I come across a problem. It appears Enchanted clothing (AKA anything made with magical materials) will cause interference, therefore causing adventurers and mages to wear as little clothing as possible. However, those same people will want practical clothing, that can protect them from monsters and the elements.
Therefore, I have to ask, How Will Practical Clothing Be Made With Magic In Mind?
To be clear, because my poor phrasing caused confusion (sorry about that), I am asking about both how clothing will be designed and what it will be designed of. Normal materials do not interfere with magic, but they tend to be inferior to magical materials in terms of durability and need for repair.