The thing that takes me the longest is figuring out the pattern on 1 sq. per inch graph paper. After I've gotten that down, I then figure the size of the quilt I want.
For me the colors just pop right in & I have no problem. I cut at the same time ALL of the fabric because I KNOW that I'm happy with my choice of colors. Sewing it doesn't take too long either - BUT I spend a LOT of time with my iron!