Eat in small proportion rather then eating 3 meals a day eat 5 meals it will really help n rest you can do as all girls r saying

Instead of having 3 meals, split them into 6 mini meals...And drink atleast 3-4 litres of water daily even if tummy feels full...It will surely help

Drink atleast 8 glasses of water in a day. Avoid spicy and oily food. For relief from acidity, drink cold milk

You should keep yourself properly hydrated. 
Eat your meals in Small portions at regular intervals 
Eat oranges more. 
Avoid oily food and outside food .; 
This is what i know 
Other mommies will give you more suggestions. 
During my early days i suffered a lot due to acidity .

How can we reduce acidity in pregnancy initial stage??