The given method claims that you can divide the flower to stages/levels/half spheres - as shown - and add some curvy petals to it.
This is the "by the book" sketch. Looks a bit schematic, but I guess that that's just the way I drew it.
These are the "real life" attempts. As you can see I drew one of the roses three times and this is why. The first attempt came out a bit messy. I didn't like the result so I drew it again. The second attempt was a bit neater, but still not that good. For some reason I thought that maybe it was because I drew it really small, so I decided to do it a bit bigger.
I think that the last version looks much better than the small ones.
So I guess there is one thing I did learn: never draw tiny. And don't save the paper that much. Draw bigger.
I guess this will be one of my tasks for the next month - draw a full size A4 Roses.