Once the paint is dry I apply a coat of varnish. As I like a glossy 'toy soldier' look I use either Gloss or Satin varnish by Ronseal or it's B&Q equivalent. I have taken to using satin recently as it does in fact give quite a glossy finish and dries quickly. A second coat can be applied - not least as I'll have missed bits first time round. Make sure to put plenty on bendy extremities like musket barrels and swords.
Some figures look better with a bit of pigment in the varnish - such as these very well detailed CTS North Koreans. Rather then clear varnish I used Ronseal Satin Light Oak. More expensive products are available but as far as I can see they're not any more effective.
Finally I stick a bit pf magnetic sheet to the bottom of the base. Why? Because I use thin steel movement bases and I like the figures to be secure...
That's the end of this series of posts - unless there's anything you feel I didn't cover.