10 Steps to take for step parents in building a healthy blended family.
1)  Couples need a solid marriage.  Set time aside from your family responsibilities for your marriage.  Plan regular daily time together to talk and be together.  This can be as little as a half hour a day.
2)  Communicate often and openly.  Plan family meetings to discuss issues that come up in your blended family.  Let the children know your want to discuss all issues that may come up as you form your new family dynamics.
3)  Develop routines and new rituals to bond blended families.  Plan to have a family day, family game night, movie night and new holiday traditions.
4) Spend time every day with your all children.  Talk and connect with each of the children in the family so all feel connected and part of the new family.
5) Step parent should be more of a friend or counselor rather than a disciplinarian.  Support your spouse in their role as the disciplinarian.  
6) Create a list of family rules, discuss them, post them.  There will need to be a new way of doing things in the family.  
7) Encourage children to have a relationship with both biological parents.  Step parent to support this relationship.  Children will resent not having a relationship with both parents.
8) Lower your expectations and go slow.  Don't come on too strong...these relationships take time to develop.  Over time, the children will come to love and respect you as a loving supportive person in their life.
9) Couple should agree on a parenting plan of how they will parent together.  Agree on how discipline will be handled.
10)  Have compassion for all parties, blended families take to adjust to each other.