skin, build
[skin]: obviously colour, but also if they're inclined to run hot or cold, do they have any blemishes or unusual markings, are they inclined to blush, are they freckled, do they tan, what does their skin feel like, etc.
His skin tone is tan, but kind of ruddy, too? I think that he tends to get red faced and blushes easily -- don't tell him that or you'll get punched -- which reddens his light tan. He's very active and on the go, which is, not only why his skin tone is sun weathered, but also why he has a lot of scars. The most noticeable is the one that runs through his right eye, but there's also more than a few blemishes everywhere else. Cuts, scars, bruises all fleck various points of his body, and Oleander, determined not to slow down likely won't be blemish free any time soon. He even feels a bit rough to the touch, as well as rather warm.
[build]: are they skinny and petite or do they resemble a body builder, are they tall or short or average height, are they lean and wiry, are they overweight, are all of their features proportionate, etc.
He's chubby, but not in a way that lacks muscle definition. Seeing him in action or -- more dangerously -- poking him around suggests that he really is fit despite the chub. Unlike others, who try to strengthen themselves for appearances sake ( such as bodybuilders ) his training is less focused on chiseling away fat and more focused on raw strength.
Thanks to his remarkably short height -- an impressive 4"6', which we will never speak of again -- his proportions are less than stellar. Arms and legs are fairly short and stubby, but [he-man voice] oh my god does he try keeping them fit as a fiddle and ready to punch tall people in magnificent fashion. He does well with his disability, not at all seeming stunted. In part thanks to the perks of being a psychic, his growth doesn't seem particularly unnatural considering his size.