I'm pretty new to this too. But what I can tell you is this. Look at my sig. The 2018 arrows coming out of my 51# bow, will get the best TPI at 680 grains. They do not benefit being any heavier. At 680, they will have 310 grains up front and an FOC of 21.1% according to Stu's calculator. The 2018 is a "too heavy" spine for my draw weight, but with more weight up front, they spine down.
That being said, they are in test, and I'm still shooting for flight. I might end up around there, but so far, I'm doing okay. When I started with the 2018's, they were about 533 grains.
My suggestion is to get Stu's Calculator, and punch in some values to play around with.