For wear and tear on Navy/Marine aircraft I would do a wash on exterior and wheel wells to bring out panel lines and details; dry brush raised details on exterior and interior surfaces. Remember access panels where mechs put dirty and greasy hands, and surfaces where boots and tool boxes will scuff. I remember having booties to wear before climbing on an F-18 hornet but that was an exception and not a rule.
A wash is a color darker than the surface you want to bring out detail in; very watery. When the excess water is brushed off and the remaining pigment dries the panel lines/details stand out. Dry brushing is where you take a brush and load it with a bit of paint, brush off the excess and apply the nearly dry brush to raised details such as cockpit knobs, switches and dials. To simulate gun exhaust stains or boot/hand marks and scuffs try pastel chalk dust and brush on affected areas. For hyd/oil leaks do the wash with reddish or brownish paints and be sure to brush/wipe in direction of airflow for realistic look. Always seal after your weathering; remember to go easy on weathering. You can always add more but sometimes you can overdo it! Good luck!
Max Tollens
"plastic surgeon"