ACT and SAT
Here are different sites you can go to. These sites will offer ways to get help preparing for testing and offer practice testing. Though please be aware that some of these sites you may have to pay to use, while others you can use for free.
Khan Academy: https://www.khanacademy.org/test-prep/sat
Test Preps: https://www.bestcolleges.com/resources/sat-prep/
Prep Factory: https://www.prepfactory.com/