If it's hard to get off you phone, there's a decent app called Quality Time where you can have scheduled breaks or take a break whenever you need it. You can choose which apps are still ok to use and the rest are inaccessible (eg, I alow texting but not YouTube). Also, try and have a ritual: do things in the same order before bed as a signal to your brain it's time to wind down. I even made a chart for myself: printed it, put it on a poster then covered it with clear contact paper. I check it all off with washable marker and I even decorated it. I keep it propped up on my dresser on a holder so I check it off each morning and night. I wash it all of once a week & start again. Good luck!
Set a time you want to go to bed. 30 mins before is that time, take a shower, eat or drink something warm, and brush your teeth. Try to read or watch tv. At the time you decided, go into bed, turn off all distractions, and close your eyes and try to concentrate in your breath, it should calm you to the point you will fall asleep.
I've started a simple 5 item list to get ready for bed. Just to start. At 9 I put the days dishes in the dishwasher, put away one load of laundry, shower, prep for bed, then listen to a short story.
Come up with a routine you look forward to and set alarms. I have the lights in my room set to a timer so they dim when it’s time for me to start getting ready for bed. For me, my lights dim, I make a tea, wash my face, brush my teeth, then get into bed, drink my tea and read, then lights out and off to sleep!