Small things are a pain to paint; not so much because of the painting itself but just because they can be a nightmare to hold.
A quick solution to this problem is to glue them to wooden craft sticks (lollipop sticks, tongue depressors, whatever you call them). I find I can get four 15mm figures on a stick and still be able to paint them without any trouble and they are equally useful for painting small detail parts of larger models, such as tank stowage. The glue you use is largely dependent on the area you have to glue onto but Superglue, contact adhesive and rubber glue all work well.
Once the figures are painted and varnished, simply remove them from the stick ready for gaming and use the stick for the next batch.