I just want to know more about Kirk's clothes. Does he wear them all the time? Does he ever wear colors other than yellow? Yellow looks good on him.
James Tiberius Kirk has had a wide variety of uniforms over the years.
Classic Uniform Kirk as seen in many TOS episodes:
Green Tunic Kirk as seen in "Trouble With Tribbles"
Dress Uniform Kirk from "Journey to Babel"
Turtle-neck Kirk from "Where No Man Has Gone Before" (h/t to O.R. Mapper for reminding me)
Evil Kirk worn in "Mirror, Mirror"
Open Blazer Kirk from Star Trek VI: The Undiscovered Country
Cold Weather Kirk from Star Trek II: The Wrath of Khan
White Tunic Kirk from Star Trek: The Motion Picture
Shapless Ugly Brown Jacket Kirk from Star Trek: The Motion Picture
Admiral "Two-tone" Kirk from Star Trek: The Motion Picture
Odd Wifebeater Kirk from Star Trek: Generations
Large black V-neck Kirk from Star Trek: The Animated Series (possibly a redux of his uniform from TOS)
And of course, ladies' favourite - Shirtless Kirk...
You can find more information here.
In the TOS-era, the Captain's tunic was actually green, with yellow marks near the wrists - this is a wraparound tunic:
Here's Kirk in a standard style green tunic:
I read, in one of the first Star Trek fan books back in the early 70s, that ALL of Kirk's tunics were Command Gold, but that a film processing error turned his Gold tunic Green in several episodes.