So far, I've just handed my kids the workbooks.
I do spend a bit of time at the beginning making sure they are forming their letters correctly, but I find the workbooks are really good at teaching the letter formations all by themselves.
If they were struggling at all, I would have backed up and done some of the activities, but my first two haven't needed it.
I do plan on doing some of the pre-writing stuff with DS2 (almost 4) during this coming year, though. I own the K manual and I think I will just do the activities from that, even with the preschool book. I never even used the preschool book with my first two (just went straight into the K book) but my DS2 is really itching to have his own books like the big kids and seems to like sitting to draw/write even now at 3.