How to speak like native speakers?

This might be a long answer, because whenever i am free i would add stuff to it.

listen to the pronunciation of "say" ( i mean the ei sound ) most of the words are pronounced that way to get a better grasp of what i am suggesting please learn the phonetics, given in almost all of the dictionaries.
Secondly, k is pronounced as kh, t as th, d as dh, difficult to explain but if you know क ख ग then replace the first character of every line with the second so that you pronounce ख when you want to speak क. like that for all the lines... this is just to give an idea.
Consider this thing that spellings have nothing to do with pronunciation as such always see the phonetic transcription of each and every read, it won't take time.
Best wishes!