Lightroom - Do I Use The Clone Brush Or The Heal Brush?

Generally, I leave the Spot Removal Tool in Heal mode when I am removing spots and blemishes from photos. Lightroom then automatically determines the best fix for the area that you are trying to heal.  However, the Heal mode doesn't always give you a perfect result; in particular where you are working near to transitions.

For example, on this subject, the blemish is right near the nose line. Setting the brush to Clone is the solution to avoid Lightroom losing the transition line. 

Step 1 - Set the brush to Clone, then select an area on the transition line by pressing the Option key (on a MAC or ALT on a PC) and picking the area just above the blemish. 

Step 2 - Paint in the normal way, using a brush with Opacity & Flow set to 100, and the brush just larger than the area you are trying to remove.

Don't forget to put the brush back to Heal mode for any other areas you need to work on!