I'm going to be honest, neither of us are really good on doing the work the same day, but I got a lot of tips to avoid procrastination and have motivation!
One of the best advice I've gotten and it helps me a lot, it's to set a a reward. For the example, "if I study for 30 minutes, I will watch another episode of my tv show" or "When I finish this assigment, I'm going to eat my favorite snack". It doesnt have to be something "big" but to have a short-term reward works wonders.
Looking aesthetic study pictures in Pinterest or Tumblr helps but only if you dont get too into it and procrastinate by scrolling on social media.
Having someone near you doing something productive while you study can be a good motivator too. It can be a study buddy, a stranger doing work in the table next to you in the library, or someone of your household (roommate/parent/sibling/etc) doing anything. Seeing someone doing something productive (whether it is studying, cooking, cleaning or other) is motivating.
What also really helps me is to start with another task and then move on into the work. I do something simple, like making my bed to get into a "productive streak" and start the school work then. I usually start with the easiest assigmement or one of my preferred subjects to get into the studying mood before the more boring/tedious/hard tasks.
Another tip I've seen people recommend so much (it never worked for me because I'm a disaster with that type of stuff but for a lot of people work really well so maybe it works for you) is to plan ahead. Have a calendar or at least a notion of when you have free time and aren't mentally tired. Like for example, if you finish early on Wednesdays, set a few hour/s to study that day. Have a strict routine. Though, like I said, it isn't for everyone
I sometimes guilt-trip myself into doing the work, which I do not recommend because it's not really healthy, but I do it anyways.
It may seem unrelated but for the studying for tests part maybe it could be good to have more interactive study methods, they are usually less tedious and maybe some of the lack of motivation comes from studying being tedius/boring
