I have a very short attention span, so for me, the best way to get homework done is to take out two or three assignments and go back and forth between them (that way I can pay attention longer to doing homework, since each assignment is on a different topic). I also play lively music in the background so I don't doze off or let my mind wander too much.
But of course, I do my best work under pressure, so for really important assignments, I wait until the last minute to do it, which I know sounds crazy, but I actually do a better job when I have to do something quickly than when I have a whole lot of time to prepare. (so warning, don't use this method of doing homework unless your brain works like mine)
The best advice I can give though, is to prioritize your assignments. It's important to set aside some time specifically for doing homework - don't just say "I can do it later" because chances are that it won't get done if you say that. Just understand you have to get it done, maybe get yourself a snack to keep on your desk so you don't have the urge to keep wandering around, turn on some music to get you pumped, and start doin that work!
