Your first ACT should be a full timed diagnostic using official material—score it, identify your weakest section, label why you missed each question, and use that baseline to set a target score and study plan. Skip the prep books until you know your starting point. Part of how to study for the ACT.
Why diagnostic first
- Establishes a honest starting Composite and section scores
- Reveals whether timing or content is the bigger problem
- Prevents studying the wrong sections first
- Gives you a before-and-after for measuring real improvement
How to take the diagnostic
- Use an official full-length ACT (free options in free ACT practice tests).
- Simulate test day: timed sections, breaks, no phone.
- Include Science and Writing only if you plan to take them officially.
- Score with the official conversion chart in the test booklet.
Review the diagnostic (same day)
For every miss and lucky guess, write:
- Section and question number
- Miss type: content gap, careless error, or ran out of time
- One-line fix for next time
Review method: how to review ACT practice tests.
Turn results into a plan
- Set a target Composite: how to find your target ACT score
- Rank sections weakest to strongest.
- Pick a study timeline: how long to study for the ACT
- Choose a plan length (one month, two months, etc.) from your study hub
What not to do
- Do not untime the first diagnostic—you need pacing data.
- Do not skip review and jump straight to the next test.
- Do not use a low-quality third-party test as your baseline.
Shorter drills before the full diagnostic? ACT sample questions for warm-up only—not a replacement.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.