The base idea behind the tips below is to let both hands stay on the keyboard so you don’t have to switch between keyboard and mouse.
Move the Cursor
Arrow Keys: Move in the text
Ctrl + Left Arrow/Right Arrow: Move over words — use to move faster
Pos1/End: Move to the line start/end
Depends on text editor: Create a multiple cursors — use to type in multiple lines or at multiple positions at the same time (Visual Studio: Shift + Ctrl + Up Arrow/Down Arrow)
Select Text
Use Shift to start a selection. Then move th cursor to set the end point for the selection
Ctrl + A: Select everything
Copy/Paste Text
Ctrl + C: Copy the selected text
Ctrl + V: Paste the copied text
Ctrl + X: Cut the selected text (Copy it and then delete it) — use to move text
Possible Combinations
You can combine these shortcuts to navigate and work very quickly. Here are some examples:
Shift + Up Arrow/Down Arrow: Select multiple lines
Shift + Left Arrow/Right Arrow: Select multiple letters
Shift + Ctrl + Left Arrow/Right Arrow: Select multiple words
Shift + Pos1/End: Select the line to the left/right
Other
Backspace: Remove the letter in front of the cursor
Delete: Remove the letter after the cursor
Depends on text editor: Remove the whole line (Visual Studio: Shift + Delete)
Tips
Move text: Select the text, cut the text, move the cursor, paste the text
Replace text: Select the text, start typing the new text
When you know other useful shortcuts you can post them in the comments and then I will add them.