Aim to (idiom)
Meaning - Try or intend to do something.
e.g : We aim to please our customers, or She aims to fly to California.
Correct usage: aim to + verb
Aim at (idiom)
Meaning - Direct a missile or criticism at something or someone; to plan, intend or to have as one's purpose
e.g: In his last speech the President took aim at the opposition leader.
He aims at finishing tomorrow.
Correct usage: aim at + noun