It is found challenging to many people who just started learning spoken English.
The problems like -
sa and sha sound, Mother tongue issue, And other pronunciation issues.
Here are some points to keep in mind to become better are pronunciation.
1 - Watch your favourite movie or tv show, and repeat the dialogues.
2 - Some rules regarding the words that have -tion, -sion, -tian, -ache at the end of the words. Work on it.
3 - Many words are not spoken in the same way they are written, Like a tomb, Asthama, receipt, restaurant, Russia, and many more. Find the right pronunciation and repeat as many times as you speak them correctly.
4 - English has 26 alphabets but 44 sounds. Many words are related to IPA, International Photonic alphabets. Like Chicago, Cheap, Custom; these words have C, but all are pronounced differently. These are sounds.
5 - While speaking English, the throat is used very little time. It would help if you worked on lips movement and tongue positions.
For example, we have got three 'bee' sounds: B, V, W. Words like wisdom, vast, bubble. In the word wisdom, the speaker needs to circle their lips. In the word Vast, the tongue's position is a little under the upper teeth, and, in the bubble, you have to open your lips with a little forced air.
Some tips -
Watch movies with subtitle mode ON and repeat dialogues.
Start learning slower songs.
Listen to the podcast, interviews, and kindle, ted talks, very, very careful.
Use good quality headphones.
Record your voice and work on it.
Read a variety of content, like a book, a newspaper, online articles.
Reduced hidden mistakes or work on small things that I mentioned above in points.
The most crucial point is that have patience and give yourself a measured amount of time. Do fun learning.