Languages
The more languages you know, the easier it becomes to learn new languages. This is because most languages share quite a decent amount of words with other languages. But this in turn is a huge negative. I've realized that the more languages I've learned, the harder it is to tell if a word is usable in a certain language. For example the English language is also a mishmash of a ton of languages and thus I involuntarily avoid all foreign words. I just can't be certain if those words are usable or not.