One common mistake I see people make with ACT and SAT prep is burning through official practice exams far too quickly. Don’t do it!
You should take one full, timed official practice test (notice I said *official*) to establish a baseline before starting prep. However, you only need to burn one test for this purpose. It’s a waste to take more than one before prep, since – without prep – there is no reason to think your score on a 2nd test will be significantly different. Even with prep, the average improvement is a negligible 20 points for the SAT and less than 1 point for the ACT!
(Notice I did *not* say that is the average improvement for *my* students – just the industry average.)
Optimally, you’ll want to take another 2 or 3 full, timed practice tests as part of your prep. But – in this tutor’s humble opinion – many people start doing full, timed exams far too soon in the prep process. You *do not* have to burn a full exam to get a measure of progress – timing a few passages, or perhaps an entire section, will give you a good idea of where you currently stand.
Additionally, don’t start doing full, timed tests until you’ve made real steps toward mastery on every section. Does it really make sense to burn an entire official practice test when you’ve haven’t even started on, say, the science section? You know going in that score is going to be dismal. Better to wait until you’re fully ready.
All that I’ve said is doubly true for the SAT, since (at this time, anyway) there are only 8 official tests available. But it holds true for the ACT as well: official practice tests are extremely valuable, scarce resources. Treat them accordingly and win!