Practice makes perfect.
Prepare for all of your exams with the help of these sample exams and exercises.
iBT (Internet-based Test) Practice materials and tips can be downloaded here: iBT Online Practice Test and TOEFL iBT Tips
PBT (Paper-based Test) Practice materials can be downloaded here: PBT Sample Questions & Sample Writing Topics
Official ACT Plus Writing Online Preparation
Preparing for the ACT Plus Writing (PDF; 64 pages, 2 MB)
Practice ACT Plus Writing Test Questions
ACT Plus Writing Test Tips
ACT Plus Writing Test Descriptions