What fingers do I need to use for hitting Control, Option and Command buttons on Apple keyboard? How do I place my fingers to press Control, Option and Command buttons on Apple keyboard? 

What is the default and correct way to press these buttons? I'm using these keyboard shortcuts: 

Command-C, Command-V, Command-Option-V, Command-Shift-V

Option-Shift-Left

Command-Spacebar

Option-Spacebar

My left hand is twisted when I try to use these shortcuts. I would like to read an article or watch a video on this topic.
There is no One Right Way™ of doing things. Just use what you’re comfortable with.

Anyway, here’s how I do it.

⌘+C, etc.: My left thumb rests on the left ⌘ key. My left index finger hits C or V.

⌘+⌥+V: My left thumb rests on the left ⌘ key. My left pinky presses the left ⌥ key. My left index finger hits V.

⌘+Shift+V: Same as above, except my left pinky presses the left Shift key instead of the left ⌥ key.

⌥-Shift-←: My left thumb rests on the left ⌘ key. I use my left pinky to hit the left Shift. I use my right index finger to press ←.

⌘+Space: I use this shortcut a lot, to open apps using Spotlight. My left middle finger hits ⌘ and my left index finger presses Space.

⌥+Space: Left ring finger hits ⌥, left index finger hits Space.