eat 4-5  times a day ,and limit it to about 3-400 calories each time.
if you are not allergic to caffeine, drink a cup of coffee .
try to avoid sugar consumption 
lift weights
Dont get dehydrated.
Sleep well.
Try to maintain your posture if you sit on the same place for long time ( at work or class).
Avoid eating before you go to bed
Avoid junk food and Beers.