I wanted to do something different from my desert camo for this, I decided on a light grey for the navy and picked up an army painter spray: Uniform Grey. Its final colour is nice and it sprays on uniformly, smoothly and thinly so no detail is lost. I set to line highlighting and it was frankly very boring looking. Not wanting to do striped camo's etc. I went for something that would keep the overall look while giving you something to look at close up. HEAVY weathering.
Here I'll talk about three methods I used to weather this up:
1st: (Gryphonne Sepia)Wash rust/oil stains:
This is about the easiest way you can add a bit more detail to your units so long as they have a light colour. If theyre darker dry devlan mud or a thinned down snakebite leather/mechrite red mix.
The idea here is to take just a little of the wash colour on your brush and then create dripping stains from areas that might rust or be heavily oiled: bolts, bolted panels, underhanging ledges, etc. Just take a little time to think about where this should be used and I'd generally suggest its a less is more technique. If you wanted to get serious you could use one colour for rust and another for oil in different areas. You can't get easier than this!
2nd Aged Chips:
The idea here is to give the look of small chips where the metal has aged and discoloured. This is underhighlighted to give the impression of light bouncing off the paint under the chip. (Sadly I only worked that out after a bit and my wings have upside down highlights. Still hopefully no-one will look close eh :D)
Above is a rear wing. I'm going to take you through the steps I used to build up these three weathering techniques to give a beaten/used/poorly maintained look. Its got a tiny bit of gryphonne sepia under its flaps' joints. I decided not to use much here as I've got lots elsewhere.
First up is the lower highlights: Take your highlight colour (for me astronomican grey) and draw smiley faces all over your armour plates avoiding the edges (they're for the next technique). Don't worry if theyre a little thick when you paint your next colour you'll paint over them a little.
Paint scorched brown lines using the smiley faces as a guide. Try and cover the thicker highlights so you are left with a very thin constant thickeness line highlight.
For the larger chips go in with a 50/50 scorched brown/chaos black mix to add a darker centre to your corroded patch. You can add a little boltgun metal to some of the very large chips to give the impression they're semi aged or perhaps recently re-chipped.
3 Edge chips and scratches:
Here you want to scratch up your edges, perfect for covering up where your line highlights have got a bit thick! These represent recent damage and continuously worn areas that don't have time to corrode before being re-scratched.
Using a thin or spread out beat up brush feather some of the armour edges with charadon granite. (I moved to the tip because the pic of this step didn't come out right!) I'd recommend not coving all of every edge I went for some of all the forward edges of my plane. If you were doing something orky you could perhaps go overboard and use this instead of edge highlighting your stuff.
Using the same technique feather boltgun metal inside the charadon granite leaving a rim of this left. If you wanted to further this technique you could try line highlighting outside this similar to the technique above but given I was trying to be quick I didn't bother! You can also do some of this on your panels where they're likely to be weathered from use around door handles, where feet will have walked or just occasional random scratches but I'd reconmmend not going overboard with these.
I'll leave you with my wing sections to give you an idea of what an area targeted with lots of all of these techniques ends up looking like. The aim is to try to build up lots of different weathering and colours to break up an otherwise dull and uniform scheme and add a touch of stylized realisim rather than everything looking factory fresh. I hope these help/give you some ideas, they're just how I like to do things!