To make a good impression: This is a straightforward way to say you want to create a favorable first impression.
To win someone over: This suggests you're trying to change someone's opinion of you, perhaps from negative to positive.
To sweep someone off their feet: This is used to describe a situation where you impress someone so much that they are instantly smitten.
To knock someone's socks off: This is a more informal way to say that you impress someone greatly.
To make someone's jaw drop: This implies that you impress someone with something so impressive or unexpected that they are stunned.
To blow someone away: This is a similar idiom to "knock someone's socks off," but it implies a more overwhelming sense of awe and wonder.
You can also use idioms related to achieving a specific goal, which can imply impressing someone:
To hit it out of the park: This idiom suggests you've accomplished something remarkably well, which could potentially impress someone.
To steal the show: This idiom is used to describe someone who stands out in a positive way, capturing the attention and admiration of others.
Ultimately, the best idiom to use depends on the specific context and the intended meaning.