When preparing dough, just use fresh curd. Don’t use even a single drop of water. And finally add a little bit of oil (Gingelly or Sun-flower) so that the dough does not stick on to your hand. That is it! Soft chapatis are guaranteed!
You don’t need to add oil on the tawa while preparing chapatis and also the chapatis are really soft.
Always turn around the chapatis often on the tawa. If you let them on one side for more than 5 seconds, then the chapati will be burnt or it will become hard. So, just keep turning them and you will see that they will be super soft!