I mount all my stamps on easy mount including clear stamps. I do find that you will get a better print by doing this, however, some of my clear stamps have needed to be washed before use, with warm soapy water, as they can sometimes be tacky.

If i am not getting a good image I also play around with the surface, sometimes I find that I need a soft sponge surface, and other times it needs to be a strong flat surface (for this i used a glass cutting mat)

I think you will only find the technique for you by playing... but I do hope this helps.

Kelly x