How To Practice

Hello. I've been playing guitar for 2 years now. I used to take lessons but stopped durning summer because it wasnt fun anymore. I want to start playing again but I have no time to practice. Does anyone have an effective practice that they are will to share. Depending on how much homework I have I only have about 30min to 1 hour of practice a day.
-Thanks
(sorry if i posted in wrong place. i wasnt sure where to place this)