Me personally wont use the Future to pre-weather because its near impossible to get that amazing flat finish again that the base colors had provided after you FUTURE, then weather, then flat coat. i someimes use a very very light clear gloss coat or none and just pin wash panel lines. then i do a hair only of airbrush weathering. THEN i use pastels, grounded but NOT moistened and applied direct with a QTip. primarily for streaking. i use brown black and grey. i use MIG 502 oils to to break up panels. then when all done i seal it with a acrylic matte varnish lightly from 10 inches. wait to dry then again till surface is flat enough. 

everyone has thier method. it all works. Ill post a pic of my current studio scale XWing for reference tnite for you.