Give the figures a wash of a dark brown and then airbrush a clear flat coat. This will help tone down the toy look. There are some great videos on how to add highlights and shadow when painting figures using oil paints. This can further enhance what you have so far.
Also to get the decals to better match the weathering you have done, take the same base tan color you used to paint the vehicle, thin way down like 70/30. Shoot a dusting of the color over your decals. Go slow and build light layers. This will give the decals a faded look.
A great start. Keep it up. You will be a master modeler in no time.