they are pretty easy to execute really.
drop shoulder: all you need is to double tap up or double tap down
both foot feint: if the player has the both foot feint ability, then check out which foot is his best. now say you're going from left to right. and you're using ronaldinho, who is right footed. when you're close to the player, just touble tap up so that he does the both foot feint. and vice-versa. you can also do it by just pressing the up directional for a lengthier time just than a tap, or you can press up right and then down right
they are pretty easy though. just a bit of practice