This guide is intended to be helpful, but there is a possibility that you already knew the contents before reading the guide.
It is not a complete guide. There could very well be things I've missed or poorly explained. In these cases, Let me know and i can add it/ reword it for the guide.
I did not check for similar guides(I really wanted to make a guide and this was my reason to finally do it)
Also, I am a windows user, and so this guide will be tuned to the QWERTY keyboard layout.
Anyway, lets begin!

For build mode: (in no specific order)
1. Click + drag on an empty space to select multiple blocks.
-This is quicker for selecting many blocks.
-Is harder to fine tune your selection.
2. Hold CTRL + left click on blocks individually to select multiple blocks.
-Is slower for selecting many blocks.
-Allows for fine tuning your selection.
3. Hold ALT to quickly rotate a block.
4. Press INS to quickly duplicate a block.
5. Press DEL to quickly delete a block
6. CTRL + Double Left click selects all blocks of the same type (Example: all 2*1 Wedges)

Outside of build mode:
1. CTRL + U hides the HUD and player names