Collecting reference pics and working from them is great general advice, it's something that everyone should do at least when starting out.
Because I don't use VMC I can't be too specific with colour recommendations but a good generic approach to painting the wooden furniture on rifles is along the lines of Colin's recommendations.
I would undercoat in a lighter colour (something like the colour of bare wood - beige, sand, even a light flesh mix can work well), then suggest the grain with a highly thinned dark colour (work from reference photos ideally), then glaze in thin layers with a dark reddish-brown colour, building to the finished colour of the woodwork*. Working in Vallejos the last thing I'd recommend is giving the finished stock a thin gloss coating, as you can see in photos of the real thing rifle stocks usually had a sheen and could even be quite glossy at times.
*If you get to trying oils at some point they're great for this because that sort of colour is naturally transparent and reproduces a varnish/oil coating really nicely.
Einion