Good luck with your practice, sorry to hear about your rotary cutter! That stinks!
I think the easiest method of flying geese is where you take a rectangle and sew to squares to each corner. If you look it up on google there are MANY sites that offer the calculations for the size you need of geese. The reason I don't mess with sewing triangles together is I don't like fooling with bias edges. Doesn't mean that you can't or shouldn't, I just think that's the easy no-think about it way.
Good luck!