How to Touch-Type
I touch type QWERTY at 90 words per minute since 1987. And touch type Dvorak Keyboard Layout since 1994.
Principle of Touch-typing: ALWAYS, use the right finger to hit the letter key. ALWAYS.
Begin, by placing your hand on the home row, as shown in the picture above.
Each column of the key, must be typed by the same finger.
For example, see the column 3 E D C ? These keys must all be typed by your left middle finger.
Now, remember, that is all there it is to touch typing. As long as you follow the above rule, if you do it 30 minutes a day, your will have muscle memory in about 2 weeks. In a month, you'll be fluent.
NEVER, ever, hit a key with the wrong finger. Because if you do, you are undoing your learning.
To type Capital letter, hold the ⇧ Shift key on the other side. For example, to type A, hold the right ⇧ Shift, then left hand pinky presses A.
The Space key can be typed by either thumb.
Finger Posture: Hit Key Straight Like Hammer and Nail
Your finger should be 90° angle to the key. You should hit the key like a nail going into a wood.
This is the same technique used by pianist to hit piano keys.
This way, you avoid finger fatigue.
Wrist Posture: Hoover, No Bending Wrist
Your wrist, should not rest on the desk. It should actually hover above the keyboard. Your forearms should be parallel to the desk.
Alternatively, you can put a thick bath towel in front of the keyboard and rest on the towel. The typical wrist-pad is too low.
Your wrist should be about 2.5 cm above the surface of the key.
The point here is that, your wrist, does not bend up. (nor bend down)
The Dvorak Layout
If you are learning touch-type, i highly recommend the Dvorak layout.
For why, see Dvorak Keyboard Layout, My Experience
Get a Good Keyboard
Your keyboard, is the most important thing, when it comes to touch-type and hand-health.
A good keyboard improves typing speed and accuracy for long durations. More importantly, it reduce your chances of getting Repetitive Strain Injury over the years.
If you work with computer more than 3 hour per day, you should not use your laptop keyboard. Buy a external keyboard.
I recommend keyboards with mechanical key switches.
I also recommend ergonomic keyboards.