Congratulations on making it to Social Sciences here in McMaster! I really hope you enjoy your journey!
I won't be repeating what the others have said here because I think they did a great job covering the basics for you. However, if you are considering internships/ Co-op you'll have to take 1EL0 & 2EL0. These courses are an advantage for Social Science students and aren't completely offered in other faculties.
They are
free courses you take them
in addition to your 5 course load in the semester, and lasts for 6 weeks only. The 1st year course will help you with time management, procrastination and getting accustomed to your 1st year. the 2nd year course is highly recommended because it will provide you with a thorough practical explanation to resumes, cover letters, interviews...etc. all university style that is.
Without taking these courses the internship/Co-op opportunities will not be offered to you through McMaster on the
Oscarplus website. You are only allowed one absence in this course or skipping two halves of a lecture which adds up to one absence. You don't get a grade but just a pass or a fail.
Also, since you are going into Sociology and as mentioned above all other courses are electives I recommend you take something that'll broaden your perspectives, especially since you are considering law. I would recommend Political Science with Dr. Todd Alway (He's awesome!) but it also depends on what you prefer. And don't hesitate to have a mix of some of the Humanities courses with your Social Science ones that's totally fine and can be helpful!
Hope that helps and best of luck!