Any tried and tested methods to prevent stretch marks during pregnancy ?

You can’t prevent stretch marks completely.. apply good stretch mark cream and don’t scratch.. you can use coconut oil or Bio oil as well..

Some say bio oil doesn't work well. anything else?

Coconut oil helps.; It minimizes dryness and itchiness.; However, if you've got to have some marks, to you will have. Ensure you don't scratch hard. Also Palmer's has an awesome lotion.; Read the page review by clicking on the link shared.

Use olive oil twice a day...its better if use extra virgin olive oil

Coconut oil is better