"I had to find his smile, his innate love of anarchy and chaos. I had to make his pain real. Great villains are born from tragic circumstances. They become dangerous when their vulnerability hardens into vengeance." [Tom Hiddleston on Loki]. Source: http://www.tv3.ie/xpose/article/entertainment-news/171076/Tom-Hiddleston-lucky-to-play-Loki
Hiddles is the perfect Loki because he works so hard at knowing him. He doesn't just "play Loki," he absolutely understands him. There are things that only Loki and Tom know about the character; Hidden aspects of Loki's hurting, pain, and therefore, his humanity.
FINALLY! A reference photo for a sketch! Thank you, people who take photos on movie sets...I would not be able to draw Loki's outfits without you. (Now, where's the other one with his full armor...) LOKI'S FULL COSTUME