1."used to do" talks about habits in past time which are now finished. However, "be used to doing" shows the feeling of familiar with the thing you are talking about; he or she has experienced it so much that it is no longer strange or new, and the tense is depended on "be". For example,
I didn't use to take care of dogs.(=Once I didn't take care of dogs, but now I do)
I wasn't used to taking care of dogs.(=Taking care of dogs was a new and difficult experience-I hadn't done it before)
2. "used to do" only has past tense, and no present, perfect forms. To talk about present habits and states, ususlly just use the simple present tense.
He drives a big car.( Not
He uses to drive a big car.)
3. Questions and negatives. Usually people use did…used instead of did …use.
What did you use(d) to do in the weekend?
I didn't use(d) to live in a house. or I usedn't to live in a house.
But the most common negative is never used…
I never used to live in a house.
I used to not live in a house.
You used not to like her, did you?(Not …
4. Get and become can be used before "be used to doing".
I will get used to living in a house.
Little by little, she became used to her new job.