What is the best way of reducing the number of hits if a search gives more than I want?
You could simply stop the search before it's finished. However, a less arbitrary method is to make the search query chemically more specific (e.g. by using options such as 'Number of Bonded Atoms'). Alternatively, you can restrict the search to only the most experimentally precise structures, e.g. by setting an upper limit on the R-factor by selecting the appropriate filter within the Search Setup dialog. It is also possible to restrict the search to Only Organics or Only Organometallics, depending on your area of interest.