If you ask most stepparents, they’ll tell you about their lengthy transition period as their stepchildren learned to respect them, obey them, and treat them like they belonged in the family. I’m sure that in some cases, the excruciating amount of time taken may have been necessary. However, I'm here to tell you that for the most part, it's not. While it might take a while before they start calling you “Mom” or “Dad” instead of your first name, the parenting part should be a matter of respect.
Remember you are the adult. That card alone should hold a certain level of respect. Insist that you receive it. It is one thing to be treated as a newcomer (which, by the time you’re the stepparent, you probably aren’t) but you should receive at least as much respect as a teacher or family friend. This should be acquired kindly and in tandem with an equal amount of respect for your stepchildren.
They already know the rules. Make sure you do, too, and then firmly enforce them. Just because you’re the new parent doesn’t mean that you have to be a pushover. True, you may have only been in the house a few days or weeks, but that doesn't mean that old rules don't apply anymore (unless you and your spouse decide that they don't). Make sure they know that you will be just as firm as their biological parent is (although, just like any other family, remember that there's always room for error and for kindness).
Know their routine because they won’t let you forget it if you forget. Know when it’s your turn to pick up Lucy from ballet and Timmy from soccer and Gigi from Tae Kwon Do. Try and remember who’s going to what birthday party or on a date, so when they aren’t home right after school, you know why. Don’t put Simon to bed early with Ruthie if his bed time is 30 minutes later, and don’t give Sam David’s lunch box. It’ll be a lot to remember, but remembering will be worthwhile when they come to you for permission, a ride, or sandwich that only you make right.
Make yourself a part of their daily activities, even if they don’t ask. If Kassi has a choir concert, be in the front row, even if she didn’t remind you on purpose. Bring snacks to Phil’s soccer practice, and make sure it’s his favorite. These little things show them you care and are paying attention, not just to your new spouse, but to them specifically.
And finally, remember that you are a part of the family. You aren’t going anywhere, and neither are they. Sooner or later, everyone will have to get used to that fact. Being helpful and reminding them that nothing has changed will make it a much smoother “transition” for everyone.
And don't forget to take this quiz to see what kind of stepparent you are!