What kind of plan should i have for afyer high school? ?

Am i too late to make one? Its my last year... & and i dont want struggles.... My last 3 yrs i didnt really try my best. But cause im lazy if i change my ways and fix my attendance and keep my grades up n stop bein lazy will i still be ok after high school? How do i make a plan? If im not too late... What should be in it.