on my diorama i am going to weather vehicles and buildings, and i was wondering whether or not to weather the soldiers slightly as well, like the boots and knee pads, things like that. any help would be greatly appreciated.
thanks for your help in advance

Yes you sure do. You do the same things to them as you do to the armor and you have it right, knees, elbows, helmets, hands, feet.
Same techniques, drybrush, pastels. A dark wash applied to an area will make it appear wet (when cloth gets wet it usually gets pretty dark).
Use the same color scheme as you did on the vehicle. You can vary the degree from figure to figure depending of the scene - not every guy is going to go through the same puddle the same way.

A good idea when building a dio, is to do final weathering on all figures, vehicles, buildings and ground work at the same time, or in the same order with the same weathering. This ties the whole scene together and then everything looks like it belongs there.
I agree with slodder to mix it up a bit as well and not have the same amount of dusting or whatever on every soldier.

I find that a wash of DARK UMBER really does a good job of bringing out the lines and details in WWII Allied and Axis uniform colors. Be careful around the skin however, as it will give them the ultimate "Coppertone Tan".... Another good way to create a wash like this is with ARTIST INKS... very good stuff.

i also like to then go back in (after the wash) and add in colors from the surrounding turf if appropriate... black boots that just shine when the soldier is plodding through dirt roads doesn't make sense... so either I use tinted plaster (for mud) or pastel chalks (typical dust) to get that final affect, be it on a soldier or chunk of rolling armor.

i love dirty soldiers, nothing worse to me than a parade ground pansy. everything to me has to have a little dirt on it. especially muudy knees and dirty boots.

Chris (++)a Pig in his element