Expose yourself to English as much as you can. Here are the list of what I did.
1. Listening to English radio/ English audiobook while driving/ cooking
(personally I like to listing to NPR radio and BBC. British pronounciation is much more clear than American English, imo)
In order to speak with English speaker, you need to have something to talk, to share, so it’s important to you to have something in your brain. If you have interesting idea, ppl will listening to you even your English is not good.
2. Read books loudly-at some point (several years) you may learn the pattern of sentences
3. Think in English, or talk yourself in English.
4. Do not waist your time to watching K-drama what so ever-watch English drama
5. At some point you need to practice writing in English, practice as I am doing right now.
6. Lastly, English speaking does not reflect your intellegence, so don’t afraid of making mistakes while practicing.
Remember also that most of native English speakers Korean is worse than you English.
Good luck. Don’t hurry, it takes time