Harry:
He'd walk up to you and ask like a normal person would.
Ron:
He put a note in a box of chocolates asking you out.
Draco:
He gave you a note saying to meet him at the Astronomy Tower. When you got there he confessed and asked you out.
Fred:
He put red dye in your shampoo bottle, and when you went to go yell at him for it he said. "Red is the color that explains all the feelings I have for you."
George:
He set up fireworks that said "Y/n go out with me?" in front of the whole school
Neville:
He gave you a rare flower with a card.
"I-I really admire you..erm, will you date me?"
Tom:
"You. Me. Dating. Now."
"But-"
"I WILL AVADA KADAVRA-"
Cedric:
He wrote a poem and at the bottom of the paper he asked if you would like to go out with him.
Oliver:
He faked an injury. When you asked if there was anything you could do to make him feel better he said, "Well, I would feel a whole lot better if you gave me your heart." Cheesy but cute.
Seamus:
His compliments were less perverted than usual. When you confronted him about it he just exploded and ranted his feelings out to you.
Dean:
He literally slid into you with shades and did finger guns. "Wanna go on a snazzy adventure called 'dating' with me?"