Aside from the answers above about looking after your clutch, the top thing that will damage the entire drivetrain is shock loading. You can feel if you're doing that - basically any time you make the vehicle "jerk" or jump or the tyres "chirp" as you bring the clutch up, you've just sent a big shock through everything from the tyres to the piston (via the driveshafts, CV's, diffs, gearbox, clutch, crank, conrods, etc. etc.) and it is bad for your vehicle.
Shock loads are many, many times greater than the regular loads the vehicle experiences and are an easy way to snap things, strip gear teeth off, etc. etc.
It also wears out things like engine mounts and suspension bushings much faster as the engine tries to twist off its mountings in reaction.
The classic example off-road is when you see someone get a wheel or two in the air for whatever reason, spinning wildly (because they've got their foot down) and then it lands & grips on the ground and something in the drivetrain goes BANG! - that's because the driveshafts and everything were spinning madly and then instantly STOP as the wheel touches down, and whatever bit is weakest will break under the shock.
Lots of off-roaders (esp. in the the US) run automatics for the reason that the torque converter cushions many of these shocks, acting like a bucket of custard. I prefer manual so I just try not to drive like a knob and to dip the clutch if the vehicle's about to take a hit.
In general, it's a reasonable idea to heed Sir Jackie Stewart's advice - driving smoothly is better all round, and faster. That's not a quote, but he did train people in that doctrine, and you can see the best drivers are generally smooth and calm.
The easiest way to learn how to drive smoothly is to place (or imagine) a very full cup of boiling hot coffee on or near your lap, and any sudden movements will spill it. That or a wedding cake on the back seat, or a cartoon bomb that doesn't like being jiggled about... you get the idea.