Hi Mark,
The colour, shading and weathering of decking is really down to personal preference and the forum has numerous posts on what other modellers have done and their results. Personally, I tend to like the look of Danish Oil, the application of each coat darkens the strips and protects the wood at the same time. For me, two coats of Danish Oil is normally sufficient. Wood stains are good, with a wide variety of shades and colours to choose from. Take a trip to your nearest DIY store, you'll be surprised by the variety on offer.
My biggest piece of advice before working on the model itself would be to try doing some test strips using differing stains, washes etc. This will give you a good idea on application and how it is likely to look, from there you can make your decision as to the best way forward for your model.
One note of caution, the using of wood stains and washes can be difficult to control, they can very easily spread out to areas you don't want them to go.
A look through some of the topics here should prove to be very helpful for you also:
https://forum.model-spac...aspx?g=topics&f=102
Regards
Alan