In theory, it’s not hard. Practice is another story though.

I was asked whether it would be easier to learn another language seeing as I have already learned Japanese.

Yes. Of course it would be.

When you learn a second language, you learn what you need to learn. That alone makes it easier.

Vocabulary and grammar is all it takes. Well, that and a bit of practice.

These come with a lot of connotations though. With vocabulary, you need to know the word’s meaning, form, and use. You need to know what it means, what form it takes in certain situations, including pronunciation, and where and when you can use it. To make this part a hell of a lot easier, you learn the most common, and therefore most useful, vocabulary first.

Grammar is a bit of a different kettle of fish. Each language has its own quirks. Learning these can be helped by memorizing some key phrases, questions, negatives, and the like, and then all you need to do is to replace some of the words with the vocabulary you’ve already learned.

Then all that’s left is a hell of a lot of practice. Reading things at or below your level is a great way to do this by yourself, but if you’re wanting to learn how to speak a language, you’re going to have to speak it (take note, Japan). Find someone kind enough to be a speaking partner, and then speak it as much as you can. Do whatever it takes to get past the inevitable embarrassment barrier, and then practice to your heart’s content.

Or at least, that’s how I’d do it.