I'm currently actively learning my 5th language and passively learning the 6th one. There's no universal way to learn a new language. What works for one doesn't work for another. Also, a big factor in how hard it will be to learn a new language are the languages you know already. If the new language is similar to the one you know already, i.e. is in the same language family, you will have a much easier time learning it. Languages are not just words, they are a way of thinking. You may find yourself having to learn to think in a new way literally.
When I start learning new language, I first focus on speech. So just audio until my ears can pick things like intonation, tones, words, and I start to grasp the sentence structure. After that, get my reading to a basic level and learn the alphabet (if necessary). Only after that do I start with some formal study to build a solid foundation. Usually, some kind of textbook series that covers reading, writing speaking, and listening. After that, I try to immerse myself in a language and learn as necessary.
When I start learning new language, I first focus on speech. So just audio until my ears can pick things like intonation, tones, words, and I start to grasp the sentence structure. After that, get my reading to a basic level and learn the alphabet (if necessary). Only after that do I start with some formal study to build a solid foundation. Usually, some kind of textbook series that covers reading, writing speaking, and listening. After that, I try to immerse myself in a language and learn as necessary.