The coins can be very hit and miss some days. There are days where she demands coins and asks will she get a coin for doing something. So I also try to reinforce that we also do things as it is a nice thing to do, so where possible I am using praise (which is hard, as she is a really hard to deal with at the moment). We tried to make sure with her first toy that she did not have to wait too long to get it, so she did not lose interest.