The internet is flooded with low-quality scans. Here is the critical warning: Do not download the first PDF you find.
Many free PDFs circulating on file-sharing sites suffer from: Muallim Sani Pdf
A quick Google search for "Muallim Sani PDF" yields hundreds of results. However, not all PDFs are equal. Beware of the following pitfalls: The internet is flooded with low-quality scans
Copy tricky rules from the PDF into a spaced repetition software (SRS) like Anki. For example: Muallim Sani Pdf
Cover the Tashkeel (diacritics) and try to read the Arabic text yourself. This forces your brain to apply Sarf rules.