Hi Rei, My method is to complete the base coat, spray with future,then set decals, then pin wash or "Blackwash",(this allows the wash to run smoothly along the cracks & creaveses, and not bleed all over the place) then to dull coat, then dry brush(the dull coat help to grab the paint during the dry brush step). and finally the dust or "muck"
Of course this order my be changed some depending on what your trying to achieve, ie: you my want your wash to bleed all over the place to represent oil/gas/dirt stains . But do keep in mind to always decal before you weather, as these markings were on the vehicle before it weathered.