Perhaps this is common knowledge. But it wasn’t common enough for me until recently. In the past when I have sliced tomatoes, I get a juicy slimy mess all over the cutting board. Then I read this tidbit somewhere and it works!
Using a serrated knife, you core the top of the tomato by cutting diagonally making a V.
Then turn the tomato over and slice down from the bottom of the tomato to where the stem was attached.
No muss, no fuss. Just a sliced tomato.