I keep getting a message. i keep getting a message saying not enough storage space. delete things

Question

i keep getting a message saying not enough storage space. delete things to make room. but i have an sd card and i was wondering if i could move the majority of my stuff onto the sd card so i have more room for my texts. and when i go to send picture messages i have to delete all of my texts in inbox, sent, and deleted messages. and trying to delete all of the texts always freezes my phone.can you help me please?