https://cgcookie.mavenseed.com/search/query?q=low+poly&category=&type=
Eat Sheep and Game Character Modeling are probably your best bets.
There's also:
https://cgcookie.mavenseed.com/search/query?q=character&category=144&type=
with intro to character modeling.
Low poly is a relative thing now. We're no longer in the PS1/PS2 days where 3d assets were forced to be ridiculously low poly.
That said, there are a fair number of lowish poly styles that are still popular because of their look, rather than optimization. 2d animated eyes, western and anime styles of doing things that are like sprite graphics. Done more because one likes the style, and maybe higher poly/pixel count than actual works from the time, than because of technical limitations. Stylized almost plastic looking hair. . .
It might be fun to see an expose on a number of common styles and what makes. . . I don't know a bobble headed chibi a chibi character.