Final answer:
The sentence can be completed using the words 'kindness', 'respect', and 'empathy', alongside 'consideration' to describe how to treat people well.
Step-by-step explanation:
The sentence 'Always be nice - treat everyone with ____,______,______ and consideration.' asks for adjectives that describe how to treat others respectfully and kindly. Words that fit well into the blanks provided by the context could be kindness, respect, and empathy. These words suggest that one should always act with a kind disposition, show respect towards others' feelings and opinions, and try to understand other people's emotions and circumstances. Consideration is another key term that encapsulates being thoughtful towards the needs and feelings of others.