There are several ways to improve your vocabulary. The evolution of a person's vocabulary can take some initiative but usually is a very easy and
natural process.

Reading - Reading Is a very effective method. It is very easy to encounter new words through reading. You can read books, magazines, comics, blogs, articles, forum topics/messages to encounter and learn new words. This is a natural way to ameliorate your lexicon because almost everyone reads one or more of the above whether or not they intended on encountering new words or not, and naturally, if they're interested in what they're reading, they would want to thoroughly understand what they're reading.

Listening - This is another natural method. There's an abundance of ways you can encounter new words while listening to someone. Through watching TV, movies, videos, listening to the lyrics of different types of music, listening to a speech or lecture, listening to a teacher, having conversations with people etc... While doing any of the above, you are more than likely to hear new words you aren't familiar with, and since most people would want to understand fully what they're listening to, they'd take the initiative to learn any unfamiliar words they come across whether it be through asking the source of the word, or searching a dictionary.

Writing - Writing original content requires creative thinking. If you want to be unique with your writing, a good way to learn new words while writing is to try to replace certain words you usually use with other words that can replace them. Using a thesaurus is usually good for doing that. This is good because the more unique a style of writing is, the closer it is to being original.

Searching - This is a method that works with all of the above. When you read, hear/listen to or are trying to write with a unique and innovative style of writing, it's only natural you search the words, you hear, see/read or are trying to replace with a dictionary or thesaurus.

Games - Playing word games is a fun and effective way to learn new words. There are a plethora of word games that can be played both on the internet and offline. The best way to learn is to have fun while you are learning, so this is one of the best ways to add to your vocabulary.

Why improve your vocabulary? Improving your vocabulary makes it easier to understand the words you read, hear and listen to. The larger your vocabulary is, the more intuitive it becomes to understanding people, books, sources of content etc... that especially consist of a large and unique vocabulary. Having a large vocabulary is very important for people who perform and write lyrics for music especially. It allows them to be more innovative, creative and charismatic with how they verbally express themselves in their music, and being innovative and creative is a significant factor with making music and even with writing in general.