I really need advise wth my gpa?

ok i am goin to 10th grade and i really wanna do good. i finished my year of 9th grade wth a 2.9. if i keep getting higher thn a 2.5 can i get a good job in my futer to raise a family? and if i get like higher thn 2.5 in highschool wll i do good in college?. i really need studying advises im not good in studying can anyone tll me how to do better?