3d beer in a glass

hi all,
i made this 3d glass with beer in it but i couldn't make it look real :(
http://www.imghst.com/uploads/mas_ab/beer.jpg

if there's anyone who'd like to tweak it here's the psd compressed into a rar file :

beer.rar

i posted on graphic request forum too.

i think u should ladd some foam to it, make it look real, also, it looks to 3D-ish