How do I improve my vocabulary?

[ScotchEggs]

Hello, I already know a lot of English words but I want to learn even more words especially adjectives because it makes you sound professional so I want to learn fancy words or just words you don't use in everyday life. 
I don't want to use the common adjectives a lot like great. I tend to say tremendous instead. Or for awful I say horrendous or abysmal. I want to learn words like that. I sometimes say stupendous instead of impressive. Those words even help you express yourself better so I need to learn new words asap.

[tiorthan]

To learn new words I read.

As enjoyable as learning new words is, remember to spend some time with the old words too.