IF you're not picky ... and have an airbrush ... all-over gray and all those pesky little details disappear!
Otherwise, as Ed said. I switch between 10/0 and 15/0 red sable brushes (my hobby shop stocks the Floquil brand and they're great), make sure the paint is not too thick, control my breathing between strokes and above all take my time. I typically wear out one 15/0 brush after one or at the most two 1/700 ships. But I have to admit, the 1/700 Haskell AKA I've been hacking away on for what seems like forever may consume two brushes all on its own.