Today's world has grown much smaller. Many people are learning second languages for travel reasons or the help in securing a job. Never before has foreign language learning been so popular. The big question is what is the best way to learn a language? Of course everyone wants the fastest easiest way to learn.
The first thing to realize is that if you already know a language so you understand how language works and all you need to do is learn substitute words in the new language you want to speak.
Consider that when you learned your first language as a child you made mistakes. You did not hear the words accurately as they were spoken so you did not pronounce them correctly. This will be true in learning a second language. You confused sounds that were similar with words that have very different meanings. This will also be part of your learning curve for a new language.
Another aspect of foreign language learning is writing and reading. If you speak English and want to learn Spanish it will not be difficult to learn how Spanish uses the alphabet because it is almost the same as English. Now if you want to learn Mandarin Chinese and read and write it, you will have to learn over 2000 characters of letters. This is a big challenge. Another way to deal with the problem is to see the Chinese words spelled out phonetically in English. You already know the rules of English and how to make sounds from the letters so this can be a real time saver.
Learning Asian languages adds another aspect to language learning that many languages don't have. Asian languages use tones. You can have many words that sound the same to the untrained ear but have totally different meanings. For example in the Thai language "mah" with a constant tone or no change means "come." "Mah" with a rising tone at the end like asking a question means "dog." Some languages like Mandarin Chinese use tones that rise and fall in the same syllable. Many people know that hello in Chinese is "nee how." The real way to say it is to say "nee" with a tone that falls then rises or wavers and the same for "how." This is where you have to train your ears to hear the same as when you learned English as a child. It is not difficult but it is different.
Many English speakers feel that grammar is important. Grammar is not so important for communicating in a foreign language. If you say "my house" or "house my" either way you will be understood. You will be surprised to learn how simple some other languages are. Redundant words like "a" or "the" are not used. What is the real difference between saying "a car" and "the car" when you speak "car"?