I used the Praxis Online Practice Test and figured it to be about 80% useful, 20% ancient information that did not show on the Praxis.
That, plus Comps notes, was all that I used. I haven't found, in my search, a Praxis study guide that was any better than that (which also beats the 20% ancient information, such as Bekesy Audiometry, that tends to come up in study guides but, from my cohort, did not appear on the Praxis in any form).
One thing to be aware of is the Praxis questions appear to come from the Northeast, so when describing Audiograms, there are some nuances that did not make much sense on the testing (what was clearly a Mild to Moderately-severe Audiogram being listed as Mild to Moderate, things such as that).
Good luck in your studies.
