Would and used (to) have very similar meanings and can often be used in the same situations. Would expresses that an activity was routine, typical behavior, frequently repeated.
We would go to the beach after school
We would put on our swimsuits
Would expresses that an activity was frequently repeated; therefore, it cannot refer to paststates, except when related to the occurrence of another activity (time-relative activity).
She would have an amazing tan by the time summer ended.
Use (to) (used in the past tense) expresses that an activity was a past habit; it occurred at an earlier stage of life but not now. It focuses on the habit, not duration or frequency.
We used to go to the beach after school
We used to put on our swimsuits
Used can refer to past states: being, possession, mind, and major, unbreakable habits (usually bad) etc.
She used to think she was very cool. (state of being)