So I've been baking quite a few things in a ring mould recently and the cakes were sticking to the fluted bottom/top of the ring mould so I'd have to reconstruct the cake when I turned it out. So off I trotted to get a new ring mould and what I bought is in fact a bundt tin. And the cakes are still sticking 
Admittedly, I have been cooking cakes with fruit in them and often using frozen fruit, which never helps, but any tips for helping the cakes turn out properly?
I haven't been greasing the bundt tin because it's that really good anodised non-stick stuff, but should I do that anyway? What's best, butter, butter plus flour or something like cake release?