Practice, watch videos, practice, watch better players, practice, play against better players, practice, emulate better players, practice, become better player.
Find a good coach, that is one who is recommended by a current good player e.g. a regional player recommends. If you get the very basics right, e.g. grip, stance, footwork, it will help you forever
Like any beginners into this sport, acquiring the right knowledge and sound technique about badminton and properly guide you to translate such information into the correct application into how you play is vital if you want to properly improve. Therefore, seeking guidance from a badminton coach to facilitate you properly should be your priority. Find yourself a personal coach or any club that offers such services. Prefabably find a group that is not to crowded ( 3-5 ) if you're into a group coaching so that your coach can have a constant watch on you while coaching. You need to strengthen all your basics about badminton first because its the foundation that you need to incorporate if you seriously want to improve further. That's why you need a coach so that he can guide you properly. In case you can't afford a coach, humbly seek advice and guidance from any experienced player that you know. In time where you don't have any coaching session or you're free from any of your social game play, prefabably locate a few hour of your time to practice and revise what you've learn with a colleague that is willing to be your practice partner. Additionally at home, watch videos of any badminton coaching and also how world class player plays and critically notice and remember the key area that you can incorporate into your basics. Above all, continuously practice and don't be shy to seek proper guidance.
