procura no gastar toda el agua caliente

USED TO ► To describe what someone use d to do or what used to happen, you should generally just use the imperfect tense of the main verb:
We used to buy our food at the corner shop Comprábamos la comida en la tienda de la esquina
... as my mother used to say...... como decía mi madre... ► Alternatively, to describe someone's habits you can use solía + ((infinitive)) or acostumbraba (a) + ((infinitive)):
He used to go for a walk every day Solía or Acostumbraba (a) dar un paseo todos los días ► To emphasize the contrast between what use d to happen previously and what happens now, use antes + ((imperfect)):
He used to be a journalist Antes era periodista
She didn't use to or She used not to drink alcohol Antes no tomaba alcohol For further uses and examples, see use