Most likely it will take more than 4 years to complete your degree.
It is NOT OK to just stop attending classes!
A general rule-of-thumb is to plan on a minimum of 2-3 hours of homework for every one hour of class time.! i.e. 12 credits = 12 hours in class a week + 24-36 hours of homework = 36-48 hours needed for school every week. Some weeks will require more time; some weeks less.
Even if your instructor doesn't take attendance, you should go to every class every time it meets!!
Just because you can stay up 'til dawn and sleep 'til dusk, don't!!
Schedule study time like it is a required class. TAKE BREAKS!! Avoid marathon studying.
Sit in the front of the class and be attentive to the teacher.
Make sure you are aware of Satisfactory Progress Requirements so you are not dismissed or denied Financial Aid Assistance.
Pick a few extracurricular activities and get involved.
Talk to your professors; make sure they know who you are.