First of all, it is mandatory to have such a grill pan, mine was taken 1 year ago from Ikea - she is a grandmother but not very good.
Now I plan to take a ceramic one, that's why I recommend you to find one too.
Put it on medium heat towards the sea and heat it very well - so that smoke comes out of it. If you don't heat it well, the vegetables don't cook as well and quickly, and they can stick to the pan.