The answer varies for different goals: A traveller won’t require full proficiency and will make do with basic phrases, whereas a working professional will want a deeper understanding. However, care must be taken while developing the basics of any topic: these can generally not be changed easily once made. As such, it is important to avoid developing any bad habits or gaps in knowledge, which may be near impossible to find and fill in later, and will keep affecting your speech or interpretation. Anyone who has researched and analysed this topic enough will have come upon the famous idea of full-immersion: wherein you surround yourself with the target language and allow your brain to eventually do its thing. Unfortunately, this takes years, requires your brain to churn tons of data: most of which may be unnecessary, and is still susceptible to flaws. Another method is to complement this with basic grammatical structures in order to see how the language functions and then make things up as exposure increases. Not bad, but I would personally recommend something else entirely, since not all grammar is important either. There are certain parts of a language that are better interpreted using pattern recognition and some that require structural understanding, rather than mere data churning. In this linguistic description, I will try to, based on my understanding, try to give an efficient algorithm wherein detailed proficiency may be achieved while optimising both brain storage and time for learning.