Thank you for all your help ^^ I just really hope i dont fk this graphics card up >.<
Over-volting and temperatures are what kill your card the fastest. Keep your temps low, keep your fans as low as temperatures permit, don't touch your voltage, and don't overclock it unless you know what you're doing. But, learn the healthy overclock ranges so you can get a boost in m/hash if you want. Overclocking raises the temperature, though.
Oh, you CAN under-volt as long as it runs stable, but under-volt too low and you won't get as many m/hash. This will also lower temps.