A way that I spruce up the basing, is to have a gander through your bitz box. Any parts that you aren't gonna use for anything, like helmets, weapons, arrows, etc, put them in a pile. Then, use glue and a knife to make it as if the units are progressing through a battleground. If you use the movement trays, get a spare banner and tatter it up a bit, maybe break the pole, and glue that onto the side
Also, in the Giant kit, you get a variety of bitz - If you make the giant as basic as possible, but still effective, you can have a decent giant unit PLUS a wealth of little bitz you can use to to flesh out the units.
In the 40K Nobz box, you get little totems - I once used some spare ones on some models, to make them look a little more impressive. From what I recall, the banner would work in FB, because it's pretty much just a chipped iron pole with an icon on the top - the icons are 40k ork tribes, but a flaming skull in FB is a flaming skull ;D