Hi,
These are the most effective strategies:
1. I disagree with 999Tigger on diet - yes do eat less but you need to reduce food intake by only 15% - it does matter what you eat - fats possess 9.1 kCal/gm, so cut down - carbs and proteins both contain 4.1 kCal/gm - difference is that protein uses up energy simply for it to be metabolised, so higher protein portion of diet helps, too.
2. Do exercises that use multiple large muscle groups i.e. legs, trunk and arms e.g. deadlift, pull-ups Larger and greater number of muscles activated of course burns more calories.
3. Use interval training: do some medium pace cycling or jogging for 10 min then jack up the speed to your max (130+ revs/min with bike) for a minute [should make you quite out of breath][try and push your heart rate to 150+ [depending on your age] for this spurt]. Repeat this alternation 3 times.
4. Drink 4 litres of water a day (hopefully there are several loos in your student hall haha!)
BEST OF LUCK!
M