Me neither, sadly. With the pigments that I got to try out when I met Rictus in England I could conclude that with pigments it's so easy that it barely takes any effort at all! Anyway, we seem to be in the same situation, and I do have some tips and tricks for you :)
Let's have a look at my centaur, it has most of my weathering techniques on it!
http://i63.photobucket.com/albums/h153/Sup...oK/IMGP3884.jpgOk, that was all done without the use of fancy pigments! Let's go through it one step at a time. I'm hoping that when I get around to painting a Russ for my army I can upload some step by step pictures but since this vehicle is already done that is not possible.
Ok, it all starts out with a nice clean base colour, be it white (as in my case), panzer grey, green or any other colour you might want your vehicle to (generally) be. Or a camo scheme, camo schemes work well too. So totally clean, just painted your regular way, with shading and black-lining in all the joints of the armour etc.
Next up, TOO CLEAN! What are you going to do about it!? That vehicle looks as if though it has just rolled out of the adeptus mechanicus showroom! We want to tone the colours down a bit and give it some dirtiness too it, and so we wash it! My usual wash is either black, or black/brown, because they work over any colour. On the centaur I went for te black/brown combo (ie. mixed black with some brown ink). When inking it is important to remember to thin the inks down with water (I usually add some dishwashing liquid to break up the inks surface tension, making it flow better over the model), and to take it one bit at a time! If you go on and wash a large area remaining in control over the paint is going to get hard! We want to prevent the ink from pooling up and running and all sorts of other nastiness, this step can easily ruin your paintjob if proper care is not taken, you have been warned!
So, how do I deal with the pooling and running paint? Two things, I have an other brush ready with which I can spread the ink out if it is pooling and even soak up small amounts of ink. For the really bad situations I keep a back-up in the form of paper tissue, if things go real bad I can soak up most of the ink with the paper tissue and try again (sometimes though this has left a quite good effect, but I wouldn't recommend aiming for that).
So with your now inked vehicle, what could we do next to weather it down? One of my personal favourites, it is chipping time! There are many ways of painting chipping, the easiest is to simply dry brush boltgun metal around hard edges and heavy wear areas, don't be fooled, just because I call it easy doesn't mean that it isn't a good method! I use it from time to time, it leaves a quite nice wear effect. You can, if you so desire also highlight the dry brushed areas with, say... chainmail (mithril silver can be used for some nice effects too).
An other way of painting chipping (my personal favourite of my personal favourite technique) is to make it look like the layer beneath the paint has rusted quite badly, or is of a brownish colour (you decide). Of course if you use, for example, green in the chipped areas when you've used... say white for the main colour you'll end up with a vehicle that has originally been painted green, and then white over that, in the chipped areas the previous colour is showing through. But let's not get ahead of ourselves here, we stick to the brown used on the Centaur. The brown needed to be dark to really stand out from the white (on darker painted vehicles this will be a problem, making the chipping stand out can be hard) so I mixed black with dark flesh to get a nice dark rusty colour, mmmm, lovely. Now, randomly paint it on hard edges, and if you feel more confident and secure in your painting try some "freehand" on the sides of the vehicle, get some basic patterns like the "scratch" down (look at my centaur, see how most of the chipping looks like something has scraped along the side of the vehicle? That's what I mean by the "scratch" pattern).
Now that we have the chippings in place it's time for the über-detail painting, bring out your small brushes! Carefully highlight the chipping in the same colour that you used to highlight your vehicle waaaaay back in step one, only, we don't highlight the upper edge, only the lower to get a sort of 3d effect (once again, look at Centaur for reference, you've got a nice big 1024x764 pixel picture as reference, use it. Or well, if you have a better example to look at use that). Now if you want to (but not necessarily) you can paint the opposite edge with a black line to enhance the 3d effect, but this is not required, it's optional.
Bullet holes = simple. Drill out, paint boltgun, and add the:
Rust, rust, rust! I paint the rust by mixing dark flesh and bestial brown, watered down slightly. I use two brushes, one to apply the paint with and one to drag it out with so there is no hard edge or line between the rust and the colour beneath. Add rust run-marks as you please in the same way. Lastly I shade the rust by applying chestnut ink on top of it in the exact same manner, apply with one brush, drag out with the other. You have to be quick so the paint doesn't dry up before you drag it out!
And mud, lovely mud. I glue on some very fine sand using wood glue (or PVA glue) to the bottom of the tracks and on the tracks themselves. Now simply paint that scorched brown, then dry brush with dark flesh followed by bestial brown. Lastly give it a brown ink and if you want a wet look some gloss varnish (I have some gloss on here and there on the centaur. It's important to NOT be careful while dry brushing, you want it to look splattered on!
That just about sums it up... I very much doubt that anyone will spend their entire day reading this entire thing but it is there for you. If I forgot anything I will add it later (I did leave out some bits that is only relevant for white colours, white is more time consuming than most other colours to paint). Questions? Ask away!
Ps, when I ran this through word to correct spelling, word wanted to change Rictus into Rectum :P