One of the ways to sound like a native speaker is to use idioms. Idioms are words or phrases that have a metaphorical rather than a literal meaning. You could overwhelm yourself trying to memorise all possible idioms that exist so I suggest you group them based on specific topics. Besides, you only need to use a few in a conversation, otherwise, your speech will end up sounding unnatural.
A nosy person who interferes in people's affairs.
Somebody who likes to socialise and mingle in social events (usually above normal, could be used to refer to a person who loves to party).
A well-behaved, virtuous person who always follows the rules.
Somebody who is not considered to be a contender but ends up surprising everybody by proving the opposite.
Hard as nails
Somebody who is tough and unsympathetic towards others.
Pain in the neck
Somebody who is hard to deal with, and often creates trouble.
Let me know if there are any other topics you wish to see here and/or subscribe to receive extra English learning goodies straight to your inbox!