I find the best way to get the correct weathering is to airbrush using a water/dye mixture. Build up the layers with several applications but allow each layer to dry well before applying the next one. Reason being, the heavy water content of the dye mixture can give the illusion that it's darker than it actually is. The application is water based so it can be done indoors in a garage or basement. Your not breathing in paint fumes only water vapor. If you use spray paint your garment can get stiff and looks artificial. Hope this helps?
Think about using different colors of dye as well! ROTJ flightsuits have browns in the weathering (probably because he was out in Tatooine and stuff) so show different gradients to make it look like he has been to other planets!