It is hard to say what exactly would work for you, since I don't know you and everyone struggles with different things and different problems. However, there are some issues that are common enough that I will guess might be a problem for you, too.
The number one, most important thing by far is your electronic devices. You CANNOT study with a phone or tablet near you. It doesn't matter if you have it on silent or even on Do Not Disturb. Many studies have shown that the mere presence of a communication device near you causes anxiety and makes you constantly worry about what you're missing by not checking it. So my biggest piece of advice is to take all of your devices (including your computer) and leave them in a different room, preferably as far away from where you're studying as possible. If you must use your computer (and I recommend you take notes on paper or print them out, so you don't have to), turn off the internet entirely.
My second biggest recommendation is that reading is not enough. Very often, students think that studying for a test means reading what they need to know: the Spanish vocabulary words, the history textbook, the solutions to the math study guide, or whatever else it may be. While reading through what you need to know is a good way to get started, it's not enough. Reading is a very passive way to absorb information, and, relevantly, it's not what you will be asked to do in a test! Instead, try writing sentences in the language you're learning without looking anything up, solving the entire math worksheet without looking at the solutions, writing a paragraph or two about your history topic, or whatever else that includes you producing something. Producing leads to much better retention of the material than simply reading someone else's production!
Finally, something that I find works very well for me is easing into the study time. I can be an expert procrastinator at times, so that I seem to find a million things to do just when I'm supposed to be doing something else, like studying. To alleviate this, I recommend you start doing related but less onerous activities first. After you have put all your devices away, start by organizing your study material: bring out any books or notes you may need, find paper and pencil or pens to take notes with, etc. Perhaps you want to take your shoes off, or get yourself comfortable in some other way. Don't include activities that would take you away from your study area, though. The point is to gradually set the mood for studying by making you aware of your "study surroundings" without actually starting the studying. All of this won't take a long time, and it might be as short as a minute or two, but since it's not yet studying, you'll find it a lot easier to sit down and do it. After a while, when there's nothing else to do in preparation for studying, your mind will also have run out of other things to think about, since you will have spent this time thinking about studying. Sitting down to it should be easier now.
Hopefully, all of these ideas help you. What will work for you, however, really depends on you. The best way to find what helps is to try many things out and note what worked and what didn't.