How to focus on homework and not procrastinate?

Get rid of all distractions. 

What I'll do is I'll come home, have a snack so I'm not hungry later and grab a drink so I don't use it as an excuse to leave my room. Then I'll shut the door, and turn off music/pc. Turn off your cellphone, ask family members not to walk in, etc.

It can be hard to concentrate when you have a lot of other things going on but remember that once you're done it's one less thing to worry about and it's always, always better to get it all done before the day before it's due when you need to cram and you're stressed pulling all-nighters.

I don't suggest taking breaks inbetween because you can easily get carried away and it'll be hard to focus again. Try instead to do your work in portions so you're not overwhelmed with too much at once. Do what's most important first so you aren't so pressured, and remember to not be too hasty and give poor quality work cause you're only cheating yourself and not getting anything out of it.