How to Learn a new langauge?

I gather the issue with duolingo is it doesn't explicitly teach you grammar and so you end up more with a bunch of vocab and may or may not have internalised the grammar of the language (and so could end up with Franglais/Spanglish or similar where you're just using vocab from the target language but in an English grammatical structure, which is wrong). It's probably fine as a tool to support your learning otherwise to help you internalise vocab over time, but you likely will need some more formal instruction to actually understand the grammar of the language you're learning.
For Chinese I think you probably really will need a formal instructor as not only do you need to learn an entire new grammar (which I gather is not overly similar to English or similar in terms of word order, syntax etc) but also an entirely new script which is an entirely different kind of script from what you've read before. There's also the tone system. You might be able to pick up speaking/listening skills at a similar rate but I believe for most East Asian languages reading/writing skills are much slower to develop. At the very least you might benefit from a structured textbook or similar.

tysm! I will look around and see if there are any classes!!
Do you think I should start with an "easy" language like spanish or just go straight to the jump with chinese?