Memory almost full what to do?

My PS4 memory is almost full. Is that bad? (I've only had it for about 5 months)

PS: I have a ps4 slim with 1 terabyte

Install larger hard drive? Uninstall a game again?

Can you get a USB stick as a memory extension

Uninstall games you don't play / need.

I can only delete, but I don't want to delete anything, I paid everything