I would suggest you take the other steps before diving into unsharp masking. For one, in 35mm it will be a real challenge due to the size of the negative. More importantly, if the negative you are working with isn't sharp due to operator faults, unsharp masking isn't going to be a magic bullet. I would say that properly done, it will give already sharp negatives an additional bite, but it won't focus your out of focus, blurry negative.
Originally Posted by lhalcong
If you aren't already getting tack sharp negatives from your camera, start with your technique, as identified above. Those must come first in any pursuit of image quality.
As others have pointed out, digital images give a heightened sense of sharpness due to the nature of image formation in the digital realm. This sharpness does not necessarily equate to resolution or, especially, overall image quality. Whenever I share a color film-based image, even if scanned and shown only on the web, I notice feedback I don't see with digital images posted the same way. Usually the feedback is along the lines of "amazing colors, how did you do that?"
Sharpness is not your only goal in pursuing image quality, and it is not a simply the case that additional sharpening means better image. Typically the opposite, actually.