The above is a good basic shader adjustment tutorial.  You will note that other objects (particularly fabrics) frequently come into Carrara with a highlight which renders them plastic looking.  Set highlight to none and fabrics immediately look much more lifelike (less reflective).  If you have something which needs a small amount of highlight don't set it to none, just adjust the color from white to a very dark grey (play with it until you like the effect).

Klebnor

Lotus 123 ~ S-Render ~ OS/2 WARP ~ IBM 8088 / 4.77 Mhz ~ Hercules Ultima graphics, Hitachi 10 MB HDD, 64K RAM, 12 in diagonal CRT Monitor (16 colors / 60 Hz refresh rate), 240 Watt PS, Dual 1.44 MB Floppies, 2 button mouse input device.  Beige horizontal case.  I don't display my unit.