There are a few points to consider when feinting.
One, is that the feint must be made with the same energy, determination and speed as a real cut, the only difference being that you do not advance the front foot and so remain out of distance till the actual cut is made.
Two, you have to sell it. The feint is a tool for manipulating the other guy's mind, inducing a bit of panic to get him to open up. It's all about the feeling you put out. You can accompany the feint with an appel (a loud stamp of the foot) to facilitate this, but it's not the only way.
Three, make an actual cut 4 and force him to parry it or be hit. Do it again. Then feint 4, cut 1. The first two cuts plant the idea into his head that this will be a real attack.
Four, continuously make little mini-feints to wear on his nerves- then drive home a real attack. Then, the next time, feint and attack. Again,it's about planting ideas in his head.

-Chris Thompson