Some of the techniques that one could follow is to make use of good pronunciation dictionaries like the one authored by Daniel Jones.There are many online pronunciation dictionaries like Webster, Cambridge etc. It also depends on the desire and the need of the person: If someone desires to learn proper American pronunciation,he/she can as well follow American pronunciation Dictionaries and if someone wants to be an expert in British pronunciation the above mentioned dictionaries are of great help. Moreover listening to the BBC, CNN and other English Television news channels are of great help. One can learn proper pronunciation by being a good listener when he listens to either native speakers or Americans speaking English. You wouldn't be surprised to find some of the Indians speaking English with the right accent and proper pronunciation these days.
listening, listening, and listening... to native speakers and English TV or radio channels, reading the story books with audio cds... checking the dictionaries based on ur preference either for British or American accent and of course practicing...repetition is very essential