You need to be more careful of the highlights than the shadows.
Expose for the highlights and just let the shadows block up, rather than over exposing the highlights. Always works better.
Velvia is a little slow, you could rate it at 40 provided you then do as above. I used spot metering on the F5 more often than not. If you have a pretty evenly lit scene the matrix metering will be just about cock on. Landscapes will appreciate a bit of -ve comp, because the scene may be evenly lit, but generally darker shades.