Great looking game! I love gaming in 54mm scale. It is a true pleasure. For me, this is the top of the mountain peak, for gaming, but I'm biased. (Could you tell? LOL!)
I would suggest making some Magic Wash, using gray acrylic paint, to bring out the sculpted details of those figures (they possess more sculpted detail than most folks realize they have!). You can use dark brown or even black, but those colors will really darken the main colors on the figures. Future/Pledge Floor Shine is no longer available, but this stuff is: Quick Shine Floor Polish, available at Wal-Mart stores, and online. Give it a try on a test figure… I think you will be pleasantly surprised on how much of a difference it makes on the look of the figure! A matte clear coat is necessary, of course, to dull the shine.
Here is an example of The Dip Technique, using Royal Walnut Minwax (dark brown), applied to a 40mm Cyclops figure: simple block painting, on the right, and Dip'ed on the left. Magic Wash is virtually identical to The Dip Technique in what it will do for your figures. Here is the same figure (far right), dried, with a matte clear. All of the Cyclops were block painted with acrylic paints, then Dip'ed, and matted.
If you use gray, it should not darken the existing colors too much, but it will really bring out the details in the figures.
I agree with 79thPA: use blue-tack to attach the figures to temporary bases/movement trays. The paper clips will scratch off any paint/coating on the plastic they come into contact with.
For permanent bases, I recommend Hot Glue to stick them to MDF (50mm squares, laser cut: Etsy, Amazon, or e-Bay), which can be decorated as desired. I do this with my 54mm plastic Army Men figures, and it works, superbly. Cheers!
