My husband’s six-year-old daughter from previous marriage has not accepted me even after one year of marriage. Any tips to make her open up to me?

Be a friend first before you try to become a 'mom'. This will take time especially if she's close to her real mom. Be patient. Don't force it. Try to get involved in activities that interest her. Get to know her and be genuinely interested in her as a person without seeking some sort of validation. She'll come around.