I would recommend sitting down and doing all your homework the minute you are done with your classes for the day. Don't wait till tuesday night to do homework assigned on monday and then turn it in on wed (classes are usually mon, wed, fri, or tue, thurs or mon, wed unless you have the once a week night class)
I did all my homework the day it was assigned my junior and senior years of college and it made it seem like I never had any homework. My nights were always really free.....my grades stayed up and I got drunk as often as I wanted.
If you have an exam - start studying 2-3 days before the exam and even sooner if you have two exams on the same day. This way you can break up the material and retain what you study. Never drink on a night that you study Bear in mind that I do not consider homework studying - studying IMO is when you study for an exam.
When you study - study in blocks of 45 min intervals with a 15 min break period. This will also help your retention.
I followed the above my junior and senior years of college - drank almost every night (sunday was recovery day, unless I drank on sunday - sometimes i'd have 14-21 day binges) and maintained a 3.5 GPA or higher. Don't think you can't have fun in college - there is plenty of time for it....freshman year and senior year will be your best years. Make the most of it man I wish I could go back and do it again!