How can I help my friend make better decisions?

ok so basically ive had this friend since i was in 5th grade,,,and shes been getting into a lot of trouble and she got put on probation for being a run a way but really her mom told her to leave and she just went to her dads…but her and her mom get into arguements all the time…and she has a reputation of “geting around” with guys but i’ve never ended our friendship over that…my mom told me that i couldnt hang out with her anymore …but i told her im not just goin to end our friendship…since we’ve been friends since we’ve been little…i want to help her but she doesnt want to listen to anymore…a while back she got sent to florida to stay with her grand parents …her parents thought that would help but it didnt…shes grounded right now…but now she hasnt been goin to skool…and its not that hard because the school she goes to is only from 7:30am-10:30 am…3 hrs.. cmon now…i talked to her today and she was telling me how she wanted to quiit school and…i told her that was stupid..shes a junior now and it would be dumb to quit now…might as well finish…i told her my brother quit when he was a senior and looks where he ended up…no where…she thinks she can get far with a GED and she cant…ya that will get her a few certain jobs but no good ones to live off of…she hasnt been to school and the days she doesnt go…shes been at a guys house…and thats what really makes me mad…because its the guy i use to talk to…but i told her i didnt care because im not into the whole smokein weed and drinkin everyday so it really didnt phase me…but i want to help her…she just wont listen to anymore…what advise should i give her???