Don’t use Select All indiscriminately
Don’t use the Select All (cornerstone) to add cell formatting, convert to table style formatting, add any type of data orformulas, or copying/pasting. You will literally be doing that operation for over 17 BILLION (with a B) cells. Use Select All for clearing formatting or deleting data. While you may be OK most of the time with copying and pasting, if there’s even a small chance that there is data in the far reaches of your worksheet, you may experience a really long delay or even an Excel crash. This happens sometimes when someone has copied a formula all the way down to the bottom “just in case.”
Don’t establish multi-row column headers
When your header row is not a single row right above your data, everything from sort and filter to PivotTables and table style formatting won’t work well. If you must have an extra row for your headers, you’ll need to cheat a little. On the row just above your data, establish your “real” column headers. These will be the ones that Excel uses for filter and sort, etc. Leave a blank line above that row and center your additional column header elements in the row above the blank one. Then, hide the blank one. Also, instead of merging cells, use Center Across Selection from the Alignment dialog box.
Don’t use Copy/Paste to duplicate worksheets
Not only is this more time consuming, but there’s always a chance you’ll paste your data into the wrong cells. That little one row or one column misstep can cost you hours of trying to troubleshoot broken formulas. Either right click a worksheet, choose Move or Copy and check the Create a copy box or select as many blank worksheets as you’ll need copies and create it once. Whatever you put on one worksheet will also populate on all of the selected ones. Use Shift Click to select adjacent worksheets and Ctrl Click to select non-adjacent ones.