I have not yet tried to duplicate a wooden look on my minis yet, so I took the time to
find some tuts that do.
http://blog.brushthralls.com/?page_id=2670
http://www.karoath.com/pages/minitips_wood.php
http://hot-lead.org/advance/texturing_wood.htm
http://www.hongkiat.com/blog/28-high-resolution-wood-textures-for-designers/
The last link is a site with wood textures. I used this as a reference when texturing wood onto a
3D object without using an actual photo (so basically painting).
It really helped me at the time. I haven't fully read the tuts but I recon if you base it with a nice midtone brown
and put in several lines (one of the tuts mentioned not to manoeuvre your hand put to take your time and
move the object rather than your hand.) than wash it
and use the same colour or mixed to make a different tone.
If you don't have a wide range of browns you can mix them up with, black, white, yellow, green, red and blue.
These give nice different shades ( I wouldn't advice using all those different tones).
If you google 'wood textures' you can find a pattern that suits you and try and decide what tones you want.
Different types of wood have different types of colours and patterns. But as lovely as it sounds you can be
as creative as you want because, you can
Try a bade, drybrush (for a grainy look) and putting in lined with a darker colour, if you are afraid of making a line
water it down and do it in small strokes or one quick one (though the last one only works for a few people)
Okay I'm going to stop typing, I'm getting way to enthusiastic about it

I'm just really curious about the result now.
~S.