When I became a stepmom, I really didn't know how incredibly lucky I was. I had inherited two of the most amazing people as my wards. I have truly fallen into a deep, lifelong love with my children of marriage and of birth and find myself richly overflowing in love for all of them.
When people ask me about step parenting, or parenting at all, I can only stress that separation of child from parent to get the perspective that your children are truly their own people, not an extension of you. If you give them the respect of knowing this and encouraging them as you would a beloved friend, you will have that. A child who grows up to be your beloved friend. Or, in my case, two beautiful daughters, to whom I did not give birth but whom I adore with all my heart, who count me as "beloved and cherished friend", no matter what.