I think that the best thing is just to search quizlet for topics and practice those card sets. Many of those sets have been created to review college classes and you can just use them rather than creating your own.
Also, it would also be a good idea to think about what you learned in a class and then create a project that is based on the learning and then post the results on a web page or on github. It might be something useful for someone else and then it also shows that you can integrate the knowledge into real life. Actual use of the knowledge also helps with keeping the knowledge fresh in your brain. So it is a win-win-win. You maintain the knowledge, you create something that helps other people and the project makes you look good.
Also, it would also be a good idea to think about what you learned in a class and then create a project that is based on the learning and then post the results on a web page or on github. It might be something useful for someone else and then it also shows that you can integrate the knowledge into real life. Actual use of the knowledge also helps with keeping the knowledge fresh in your brain. So it is a win-win-win. You maintain the knowledge, you create something that helps other people and the project makes you look good.