USED TO expresses a habit in the past

e.g. when I was a child I used to drink milk, but now I don’t.

The negative form of USED TO is DIDN’T  so the verb goes back to the base form “USE TO”

The question form of USED TO is formed with DID + base form “ USE TO”

 e.g. I didn’t use to like fish but now I do

e.g. Did you use to wear a uniform to school?

TO BE USED TO indicates that you are accustomed to something and it is followed by a noun or a verb in the –ING form (e.g. waking up)

e.g. I am used to waking up early, I do it everyday!

The negative form of TO BE USED TO is NOT TO BE USED TO

The question form of TO BE USED TO is formed with the negative form of the verb TO BE

e.g. I am not used to watching TV at night

e.g. Are you used to having pets?