I honestly only studied when I felt like it. If I wasn't in the mood, or I was too tired or whatever, I wouldn't pressure myself to study because I rarely got anything done. Instead, I watched the tv programs I'd recorded, eat lunch, do whatever, and hopefully get a few things out of my system. That way, when I WAS in the mood to study, I'd study my butt off to make up for it. I honestly think this was the best way to do things for me.
Another thing I found helpful, was planning a lot of social stuff on the weekend, or planning to see a friend on Wednesday (my day off, because my only class was English so I just didn't go). That forced me to do the work I had to do in order to reap the rewards of going out, or seeing a friend. If you have too much time, you just think "oh I can do it later", but if you're plannning to go shopping at 2 (for example), then you need to get everything done.
Another idea, because Wednesday was my day off, I'd decide that if I got a lot of work done on the weekend, monday and tuesday, Wednesday would be a relaxing day and I wouldn't do any work until the evening, but if I didn't get enough work done, I'd use it to study. I almost never used Wednesday to study unless I had nothing else to do because I'd be really motivated to study if I knew the reward was kicking back, or seeing friends.