Typically, raking a mast back will induce more weather helm. I like a little weather helm. It gives tactile feedback on the tiller and will keep the boat from sailing away if you fall off. I also find that a bit of weather helm helps me point. Too much weather helm induces excess drag (slows you down).

So, I rake the mast to the point where I have just enough weather helm to feel it, but not more than I can control with my fingertips.

I hope that helps,
Eric