This is a tough question to answer because it all depends on the type of schools you want to apply to. A strong score for one school may be a noncompetitive score for another school. Instead of getting fixated on a particular test score being a “good score”, I recommend two things.

Take practice tests so you can start to determine your testing abilities, strengths/weakness, and you can start to see what range you are testing within. Or work with a testing expert to help you to determine your testing goals, the scores you will most likely achieve, and determine testing abilities and limitations.
Start identifying schools you are interested in and check out the average test scores. Typically colleges will either post the middle 50th percentile test score of their accepted or enrolled freshmen students.
A great resource to use to check the average ACT and SAT scores for accepted students is by going to Collegedata.com. Collegedata has wonderful admissions information, so you can determine if you are a competitive applicant for admission based on the GPA, test scores, and more. When you go to Collegedata type in the name of a school and click on the school link. When you are on the school profile page, you will want to click on “Admission” and scroll down to see the “SAT Scores of Enrolled Freshmen” and “ACT Scores of Enrolled Freshmen.” I appreciate that Collegedata posts the score breakdown into details as you can see in this example below…

SAT Ranges

Watch my video to learn What Is A Good ACT and SAT Score?