A vocab primer pdf or website with like 200 of the most common words and phrases & listening to people talk is probably going to get you through the majority of conversations. Word frequency in natural language follows a Zipf’s law distribution, so focusing on the most common words & phrases first is very efficient.

Practice, spaced repetition, and quizzing for memorization and long term retention. Beyond that learning verb conjugations and maybe a English/Spanish book that has one language on the left page and the other on the right for more expanded vocab and variety.