Question

what is the proper and safe way to dilute acid with water ?

Answer 1

i think we should add water to acid

Answer 2

Safety: ALWAYS add concentrated acid slowly to water and NEVER the other way around.
If you do it the wrong way around you get a very rapid exothermic reaction - it gets hot very quickly, producing lots of dangerous steam and spitting everywhere.
Ideally you should use a fumehood (turned on), safety glasses and thick loose-fitting rubber gloves (in case you need to remove them quickly). If a fumehood isn't available do it outside on a solid unreactive surface and in a good breeze.
Make sure you have ready access to clean running water in case you are splashed.
It's also a very good idea to make sure someone else knows what you're doing and is nearby (within earshot).
Concentrated acid should not be used around flammable materials, because there is a risk of ignition.

Accuracy: Use a volumetric pipettes, volumetric flask and distilled water to make your dilute.

Bear in mind that acid should not be used with certain other chemicals. Likewise you should use glassware and not plastic.