I am using (or trying to at least) the Fiskar's shape cutter to cut pictures and cardstock and it does not seem to work. It seems to leave a line where it is supposed to cut the pictures but it does not cut them at all. It worked fine when I first bought it and I have even replaced the blade but the results are horrible. For paper and cardstock it does cut but leaves a few sections that are not completely cut.
Everyone's suggestions here are right on target. Other tips are to hold the cutter like you would hold a computer mouse. Also, the Fiskars cutter does not easily go through heavy cardstock. When using heavy cardstock, expect to go over the area a few times, or do some additional hand-cutting for the missed spots.
One more suggestion.....Fiskars has very good customer service. If all else fails, give them a call. The intake person will give you suggestions, and if needed, give you instructions for replacement in the event that you have a faulty unit.
Both Ms. Jackie and I are Certified Fiskars Demonstrators.....so PM either of us if you have any more questions.