For Modern in the International Style I would recomend Dance Vision 4. Richard and Janet Gleaves. Too many tapes just give a whole heap of variations. This one tells you about your centres and how to keep your centre to each other. Also in the V. Waltz Natural turn, 6th step ball flat not TH. and keep the toe down on the floor on the completion of that turn. And so it goes on. Head position for the lady in a Natural Spin Turn Modern Waltz for a better effect and balance. Also I would recomend if it is still available John Woods and Anne Lewis on the Waltz and Foxtrot. There is a lot of good advice on that one also.