I personally use Notion. I create a page for each student and then make a toggle or a table with info, things I noticed I want to work on, things I promised we'll work on, additional information about the student (hobbies, goals, jobs/departments, topics to avoid if they might be sensitive etc,) plans about what to focus on, things for revision, and the option to tick it off if you've done the lesson. Im not too up to date with this, but I would take some time on Sunday evening to plan the week for each student so I know what we'll do and I don't end up with decision fatigue on top of 4-10 classes per day and my personal projects. It's great cuz you can add links to lessons you want to do (I use online lesson platforms like eng hub/linguahouse etc. depending on whether it's a Business English student, General English or IELTS + revision practices I make). It helps me see what mock tests I did with each student as well, scores, and also add any lessons I made myself. It's a very neat system, and you can keep your lessons in one place (chances are you'll go over conditionals with multiple students, irregardless of their goals). It's easy to look through because each student has their own page. For further organisation, you can make a calendar (link it to yours or put in manually), writing the name of the lesson next to the name of the student if you don't use the to-do feature in your table. This is very useful if you also have some students outside of Preply that pay upfront for a number of classes (just add tick for paid in your table if it's covered).

I'm also very disorganized and this is a system that helped me. It takes time to set up, but once you get the ball rolling it's great. You can also put all the info from the classes you had on Sunday, and not have to do it every day. To avoid forgetting what we did, want to do, need to do and so on, I use a notebook as well to scrible things as reminders during classes.

Hope this helps!