Your first order of business is to gain motivation. Whether your homework is due in an hour or you want to knock it off so you can enjoy the weekend, motivation is key. Remind yourself that if you get your homework done right now, you will not have to worry about this specific assignment ever again.
First, try visualizing yourself doing your homework. This may seem corny and simple, but it can get you mentally prepared to sit down for some length of time and do your work. Remind yourself of how long it may take you to do your homework and realize it will end eventually.
Next, create a useful workspace. Ensure your basic needs have been met before entering said space: you have gone to the bathroom, eaten something, and are not thirsty. You are neither too cold nor too hot. Choose an environment with a workable atmosphere. Do you need complete silence? Do you like to be around others who are working? Maybe the library is for you. Or you can be completely cliché and go to a Starbucks, but hey, whatever works. Find a place you can concentrate in.
Set up your area with minimal distractions, i.e. giving yourself 10 minutes to get whatever it is you want to do (Facebook usually) out of your system then putting your beloved phone on airplane mode. Have a water/tea/coffee readily accessible.
Do you study/do homework with music? Put on a playlist and don’t touch it. This will lead to much wasted time.
Give yourself small goals and rewards. For example, if you complete three whole pages of your essay, reward yourself with 5 minutes on your phone.
If studying a difficult subject, maybe studying in groups is good for you. Just ensure you focus on the topic at hand. Surround yourself with other students who can be academically oriented and have good study habits that you can emulate.
I’m reading A Speaker’s Guidebook