The best way to improve English speaking skills is to speak in English as much as you can, there is no other substitute to it.
Sometimes, when you don’t have the environment where you can speak in English much then you should at least “Think in English”. This way you stay in practice and will not forget the vocabulary and the grammar (because of not using it). Also, it will eventually help you to develop your thought process in English.
This is a great way because this activity will fit easily in your busy schedule and can be done anywhere. You can think in English about the story of a movie, a past conversation, a past incident,etc. Other than the above, if you can afford more time to the practice, you should also go for reading books and watching movies and programmes (with English subtitles).