Once your FG are made and you want to sew them together tip-to-base, it's important to pin correctly so you don't cut off the point. There are a couple of ways to do this.
One is to use an ironing board and a straight pin. Place the FG with the point on top, and run the straight pin straight down at the point. Add 2 pins to each side, and remove the straight-up-and-down pin. When sewing, keep that side up so you can see to sew just 1 thread outside that intersection. That one thread of space allows the turn of fabric so the point is kept.
I prefer glue-basting to pinning, which is similar to the above but instead of placing the 2 pins to the side of the straight up-and-down pin, I use a tiny dot of Elmer's white school glue in the seam allowance and dry with a hot iron. Again, it is important to sew with that tip up so you can see that you are not sewing part of the tip into the seam allowance.
You also need to pin accurately when sewing columns together.