Why is it important to use good technique while keyboarding?

Posture: You should be sitting upright with your feet on the floor. Your wrists should float an inch or two above the desk/keyboard (NOT resting on them) And the keyboard should be at a level so that your elbows bend approx 90 degrees. Wrists should be straight.

Fingertips should rest on the "home row" keys... asdf for the left hand and jkl; for the right with thumbs over the space bar. Assuming a standard QWERTY layout of course.

The keyboard should lie flat on the desk, not slanted upward, do not use the retractable legs on the back of the keyboard to tilt it.

Consider a split or "wave" ergonomic keyboard. Once you get used to it, you may find it much more comfortable. In all respects a good quality keyboard can mean the difference between severe pain or years of uneventful typing.