There are multiple resources to take advantage of and a majority are free. You can visit the College Board web page and they provide free example tests for the PSAT. College Board also provides daily questions to help you practice in various subjects.
If you’re looking to review the material that might appear on the exam you can also look into checking out the books at your local library either online through any digital apps the library might offer or picking up a physical copy. Libraries carry a variety of example test or section reviews of exams including the PSAT.
Many students have used various platforms such as YouTube, Wyzant, and Khan Academy to find lesson reviews of the material that could pop up on the exam.
When studying always try various methods and see which ones stick best in helping you remember, for example I do better with flash cards and rewriting notes in a simple three color coded pattern (one color for each specific subject) so the information stands out but still remains organized when processing it as a review. Always try to go back every so often to re-cap the material and then build from there to incorporate the newer material you have just reviewed.
I hope this helps, if you need any more pointers you’re more than welcome to reach out! Good luck, you’ve got this!