Ctrl-Shift-V (Command-Shift-V for Mac)
If you use Ctrl-C to copy, Ctrl-X to cut, and Ctrl-V to paste, this one is for you. Ctrl-Shift-V (Command-Shift-V) will allow you to paste using source formatting. That means it will match the formatting of the document you are pasting into. For example - I am typing an email and I want to copy some text from a document or website that is using a fun font and green text. I want the text to be black and in the same font and size as the rest of my email. If I use Ctrl-V to paste, it will most likely keep the font, color, size, and line spacing from where I found it. If I use Ctrl-Shift-V, it will match the font, color, size, and line spacing of my email. Talk about a time saver!
Holding Shift while Making a Shape
In apps like Google Drawings and Google Slides, when you make a shape like a square or a circle, there are times when you don't want it to shift into a rectangle or a circle, you want it to maintain its shape as a perfect square or circle. If you hold the shift key down while you draw the shape, it will stay true. For a triangle, it will keep it equilateral or isosceles, depending on the one you chose to make. For an arrow or a line, it will keep it straight and not let it become slanted. If you drag up or down far enough, it will snap to a diagonal, but it will prevent you from doing the slightly not straight line. This is a life saver for making all my tutorials! I know it works in Drawings and Slides, and also in Preview on a Mac. Try it in whatever program you use that makes shapes or lines and see if it works - I bet it will!
Both of these tips saved me a bunch of hassle once I learned them. I hope they save you some time and hassle too.