The antonyms for the phrase "lay it thick" are quite a few. Some opposite phrases that come to mind include being diplomatic, subtle, cautious, and restrained. Instead of being excessive with praise or criticism, one can opt to be more circumspect and measured in their statements. One can avoid exaggeration, be objective and rational, and deliver feedback smoothly without sounding harsh. It is also essential to consider the audience and deliver the message appropriately. Avoiding being too forthright can foster a more positive and constructive conversation. By doing so, you could prevent others from feeling uncomfortable or attacked, and instead, promote a positive and cooperative environment.