This is a no-brainer, but so easily overlooked. You start typing a series of repetitive things like dates (1/1/20, 1/2/20, 1/3/20, etc.) and you know you’re in for a long day. Instead, begin the series and move the cursor on the screen to the lower-right part of the last cell—the fill handle. When it turns into a plus sign (+), click and drag down to select all the cells you need to fill. They’ll magically fill using the pattern you started. It can also go up a column, or left or right on a row.
Even better—you can Auto Fill without much of a pattern. Again, pick a cell or cells, move to the fill handle, right-click, and drag. You’ll get a menu of options. The more data you input at first, the better the Fill Series option will do creating your AutoFill options. Check out this Microsoft tutorial.