Try to read her body language. You can gauge her interest by noticing her eye contact, smiles, laughter and enthusiasm. The first thing you have to do while asking the girl out is to have a plan for the date. You must know the areas of her interest and activities. Tell her in a tranquil way, that you are going to visit or do something, of her interest, this weekend. And then ask her, would she like to tag along? If she says no then don’t take it personally and keep yourself cool. Don’t loose your heart and continue to make effort. But don’t try pressure and harass her. With the passage of time when you both know each other well, she might ask you out.