ACT and SAT
If nothing else, I highly recommend all of the following:
Study. Neither of these exams test pure "IQ," they are tests that can be mastered and manipulated. The more you know and practice, the better you will do. Period.
Buy a study booklet and work through the entire thing. That means you break it up into manageable portions and you accomplish each section in advance. Please don't wait until the night before, it will be too late. There is an entire section at Barnes and Noble or you can find them easily on Amazon. See my recommendations below for full details.
Realize that these standardized tests are not the defining factor for college. They are simply another (although powerful because of their "objectivity") factor of comparison between you and other college applicants.
I would highly recommend you participate in one of Mr. Chilton's study sessions. See this flyer for more information. I know I'm kind of biased, but it is very helpful to attend these sessions to get guidance from a pro and have a structured way to prepare.
Resources:
Which one? Take the SAT or ACT? Use these guides to help decide:
The following are all "official" test preparation materials from the parent companies that host the exams. This means they can be trusted and are extremely useful, if not a little sparse or not as detailed as other resources.
SAT:
Homepage: Click here
Practice: Click here
Study Plan: Click here
Question of the Day: Click here
Full and Free SAT Practice Test: Click here
Answers Explained: Click here
Skills Insight: Click here
Register: Click here
ACT:
Homepage: Click here
Test Descriptions: Click here
Preparing for the Exam (Free resource PDF: A must have!): Click here
Basic Tips: Click here
Practice: Click here
Online Prep (paid service): Click here
Prep Booklet: Click here
Question of the Day: Click here
Sample Test Questions: Click here
Register: Click here
Unofficial Resources:
YouTube Playlist from Kaplan Test Center. Great resource for everything SAT & ACT related in video format: Click here
Study Booklets:
SAT
Amazon Search: Click here
Official Study Booklet: Click here
Practice Question Study Guide: Click here
Recommended "unofficial" reference: Click here
ACT
The one and only "official" book: Click here
Recommended "unofficial" reference: Click here