I’m going to be a freshman at UT Austin majoring in biology. Which courses would be the best for me to take?
You will have an advisory session when you go to orientation, and they will help you get started by going over your major requirements and choosing courses for the first year.
Start here: https://cns.utexas.edu/students/degrees-majors-advising/degree-checklists#biology
Find the appropriate major, and go from there.
And, yes, you will meet with an adviser before choosing your courses.