how can I improve my spoken English

First, you will need to decide whether you are learning American English or European English as there is a very distinct difference in sound, vocabulary, pronunciation and much more. Once you have decided this factor then it is PRACTICE, PRACTICE, PRACTICE, PRACTICE and MORE PRACTICE!

Spoken English is best improved when practiced with native English speakers, online or in real life. You can use a lot of apps that provide service for talking with native English speakers. They are easily accessible online.