Since I've done all 36 blocks that way, so far only a few presented problems. For the few that would, I traced the pattern on freezer paper and then turned it over and retraced the lines on the back side. I didn't trace the entire pattern, only parts of it to help general alignment. I was more concerned with getting the blocks liked up with each other - such as having hearts touch at points (to give a circle look) because that is more important. There is a lot of flexibility with these.
One more note - if you are machine appliqueing, you may want to cut some pieces long where they go under another piece so that you only have to stitch on the upper piece. If you butt them all up, then you have to either us a larger stitch and overlap, or to two rows of stitching.
I would put a little tick mark on sides I wanted to extend, as I drew the pattern as a whole on the fusible web, and cut them out like that. I'd fuse them and then cut the fabric extended where I wanted to tuck them under.