Have used Army Painter Quickshade, and impressed with the results, but can be a bit messy and seems hard on brushes when trying that approach.
Over on TMP (theminiaturespage.com), it always starts a debate over home made washes etc.
So, after reading several different formulas, here is what I tried today.
Used Pledge Multi Surface Wax (formerly known as Klear), some water and GW Chestnut Ink (as I had some already).
Used a spoon which came with some kids medicine. Has a 5ml spoon at one end, and a 2.5ml spoon on the other.
Put 5ml of Klear, 10ml of water and 2.5ml of ink in a jar and stirred it around.
Had a Celtos Sidhe Retainer painted and waiting for next steps. This became the guinea pig model.
The wash has gone into all the creases and folds pretty well., bringing out the detail. I'd used lighter colours for base coat as they then get "knocked down" a shade or two following washes/shades.
May add a few highlights and details before hitting it with a spray of matte varnish and see what the end result comes out as.
Even using small amounts of Klear, water etc., there's quite a bit of the mix left, so have put it in a small airtight jar and will use it on the other models when they're finished.