During the course of the game Squall seems to change clothes only a few times (three o_o). A few things stay the same in each outfit-the necklace, the hair, and the frown ^_^. Read on for some more information.
The Normal Outfit
Squall wears this almost all the time - he seems to like black a lot ^_^. His jacket is made of leather (presumably), and resembles one of those bomber jackets from World War 2. Except for the strip of fur around his collar, but I guess they put that in to resemble a lion's "mane" . Underneath that, he wears his Griever necklace and a white shirt. His gloves and pants are all made of black leather as well. On his waist, he wears one big gray belt, two red belts forming an 'x', and three smaller silver-ish belts on his right thigh. His boots are black-again-and go up to about his knees.
The Field Uniform
Squall wears this outfit only in the field exam in Dollet :-(. His jacket is dark blue (it appears black in the FMV's, but it is actually blue ^_^), with circular, silver designs embroidered onto the collar, breast pockets, and sleeve cuffs. On his waist, he wears a black belt (with a fancy little silver buckle). There's nothing really to say about the pants...they're just blue.
The SeeD Uniform
Now this is an interesting outfit ^_^. Squall wears this to the SeeD inauguration ball. The collar of his coat goes right up to his neck, with yellow lining going through the bottom and center of the coat, as well as the bottom of the neck cover thing (can't think up the right word for it...). Squall's collar is also adorned with blue cloth and the same colored embroidery as in the field uniform, but more detailed. His cuffs are a velvety red with gold lining, and his pants are dark gray (and probably not leather).