When I was a child, I would walk to school every day. (A repeated action in the past, spoken formally)

I used to have (OR I had) a car but I wasn't very good at driving so now I just take the bus. (having a car = a state that isn't true any more)

He used to have short hair / he had short hair. NOT he would have short hair. We never use 'would' to talk about a state in the past.

She used to be (OR she was) my best friend, but then she stole my boyfriend so we don't talk anymore. (State that isn't true any more)

I used to live (OR I lived) in a huge house by the beach. (A state that isn't true any more)

I used to play (OR I played) tennis at the weekends but now I'm always too busy with work. (A repeated action in the past that isn't true any more)

When I was young, my mother would pick me up from school every day. ( a repeated action in the past, spoken formally)

I used to be (OR I was) fat but then I went on a diet. (A state in the past that isn't true any more)

I used to get annoyed by him, but now I think he's funny. (repeated action in the past that isn't true anymore)

I ate sandwiches / I used to eat sandwiches / I would eat sandwiches

When I was a kid, my grandma used to kiss (OR grandma kissed) me on the lips whenever I saw her. I hated it!

When I was young, I would have piano lessons. (a repeated action in the past, spoken formally)

I used to know (OR I knew) everything about Harry Potter, but I've forgotten most of it now. (a state that was true in the past but isn't true anymore)