The most important thing you’ll need to learn a new language is interest. Without it you’re pretty much guaranteed to fail. I’ve mentioned this before but it deserves mentioning again.
There are two kinds of interest, Direct and Indirect. When you have a Direct Interest in the language you feed your interest by simply studying the language. This in turn ensures that you continue studying, even when things get hard, even when you run into a wall… especially when you run into the same wall several times. If you have at least one Direct Interest it can make or break your language learning.
On the other hand an Indirect Interest is when you don’t actually care about the language, but you’re learning it to feed some other interest. Like getting a job or impressing someone. In a case like this, the only time you’re going to feel rewarded is when you reach that goal and it’s more likely that you won’t be able to maintain interest in the language long enough to do that.
I’m not saying you absolutely can’t learn a language if you have an Indirect Interest, but simply that your chances of success are much lower, unless perhaps you have a few Direct Interest reasons as your primaries.
The reason why interest is, in my opinion, the most important thing and comes before having a good method and all the other necessary things, is because methods and other things can fail, you can fail. We all do. But if you have interest, you’ll keep going and find a way.