How do you recommend learning Korean to a complete foreigner?

I'm a student and there are very few native Korean speakers, diaspora, or structured Korean language courses in my country (not that I could afford those anyways). I have almost no exposure to Korean media or pop culture except for the global hits like Squid Game / Lovely Runner and Butter / Dynamite. My goal is TOPIK Level 3 proficiency (or near 4 if possible), and it's strictly for academic purposes as I plan on enrolling and studying in a Korean Institute in the next couple of years. I know millions of free resources exist just like japanese for people obsessed with k-pop and k-drama, but I don't want that. I prioritize speed, efficiency, and politeness over sounding natural or native. I haven't done enough research as to know what the best resources for learning the language free online are, and it'd be great to save myself the headache if someone has already gone through a similar situation and handily compiled a similarly structured free roadmap for me to use. I'm not asking for someone to practice the language with or anything like that, but rather just advice and resources for learning it ASAP and without making the mistakes most beginners do (even though ironically the best way to learn anything new is to make lots of mistakes). Any help would be greatly appreciated!
I'm also sure that a similar question may have probably already been asked somewhere else and I missed it while searching, so please just link it in your answer instead of calling out my stupidity as it's really not that big of a deal.