Simon -
I'd have to say that as things get smaller in scale, I find that a set of magnifiers (the ones that sit on my head and can hinge up or down) are very useful - they can allow a much closer look at what you're doing and will give even larger fingers a helping hand (no pun intended).
It's often easier to make very small movements with your fingers if you have a magnified view. Consider the delicate surgery opthamalic surgeons perform - they don't trust their patients eyesight to the good old eyeball Mk1, do they? I use them, even though I've got 20/20 vision. They're a big help. Give them a try.
Cheers,
LeeTree