I’m trying to think of a phrase which means that being nice to people can be a better way than to be horrible and forceful to people. Can someone help me out?
The phrase you are looking for is “You can catch more flies with honey than you can with vinegar” and it was the subject of a previous question here on ELU.
Sometimes the carrot works better than the stick.
carrot and stick.
COMMON If someone uses a carrot and stick method to make you do something, they try to make you do it, partly by offering you rewards and partly by threatening you. [...] Note: Carrot and stick are used in many other structures with a similar meaning.
Protests continued, however, so the authorities substituted the carrot for the stick. When the Security Council waves a stick at an offending country, the secretary-general can also offer a carrot as encouragement.
Note: The idea behind this expression is that an animal such as a donkey can be encouraged to move forward either by dangling a carrot in front of it or by hitting it with a stick. The carrot represents the tempting offer and the stick represents the threat.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
A fairly well known idiom is ' the softly, softly approach'.
An interview with Ivana Trump on Good Morning Britain has raised a few eyebrows after the normally combative Piers Morgan adopted a softly-softly approach to questioning.
The original expression was 'softly, softly catchee monkey' coined in the late nineteenth century, meaning :
Proceed cautiously or gently to achieve an objective.
But the simplified expression seems to have a wider usage and a broader scope :
(British English, informal) a/the gentle, patient and careful way of doing something, especially when dealing with people: The police are now trying a more softly-softly approach with football
The Ngram of 'softly, softly' against 'catchee monkey' shows that the shortened expression is far more common.
It also seems to be more common in BrE than AmE.
Bill has become so sensitive. You really have to handle him with kid gloves.
Also, treat with kid gloves.
Seems to be the opposite of:
Handle without mittens (or gloves): to treat without any superfluous politeness or gentleness; to attack vigorously [with example given from the North American Review, 1887]
The latter is apparently the origin of gloves are off.