I've been a stepmother three times. I know, from hard-won experience, that a great relationship with your stepkids is possible. And if you avoid certain trapdoors like the 12 verboten phrases here, you'll not only get along, but you'll never have to ask them to pick up their socks.
1. "Go ahead, call me Mom!"
You're not their mother, and you never will be. They're conflicted enough, and pushing them to use a mom-name will only confuse them more.
Corollary: "We're going to be one big, happy family!"
You might eventually become the happiest of stepfamilies, but it won't happen overnight. Studies show the new family dynamic takes at least three years to fall into place, and the first year is the toughest.
2. "Feel free! Do whatever you want."
Almost as much as they need love, children need boundaries, and are adrift without rules. Learn to say (not scream, please) the following phrase: "In this house, we..." so that time together will not be bogged down with endless negotiations.
Corollary: "Let's get down!"
No matter how close in age you are to your stepchildren, you're still a parent figure; try to be an example of mature living and not 'one of the gang.' This is especially true if your stepkids belong to that group of psychotics euphemistically known as teenagers. Chances are they won't think you're cool for very long.
3. "I'll get it," "I'll drive," "I'll wash it," "Forget about me," etc.
Don't let your stepkids (or their father) turn you into the creature everyone in the world resents: a martyr. Martyrs make people feel creepy and guilty, and when kids feel that way, they generally act out. You're better off being wicked.
4. "Why the long face?"
Your stepchildren are allowed to be sad—they're in mourning. Let them grieve if and when they feel like it. Sorry, but they probably will grieve more around you, since you're the evidence that their parents are never getting back together. Don't call attention to their sorrow; remove yourself, and get Dad to be a mom at this point. Their depression will pass—they're kids.
Don't allude to the great times you have with their father when they're not around. They already feel left out, and probably imagine the two of you tossing your heads back laughing, spending wads of money, and throwing Ring Ding wrappers on the floor (not to mention the sexual fantasies going on in their fevered little brains). If you want to give them a positive image of a loving couple, just be a loving couple.
6. "Did your mother bring you up to do that?"
Never bad-mouth the ex—and your husband (or partner) shouldn't either, even if the fur is still flying. Studies show that it's the ongoing conflict after divorce that hurts kids the most.
Corollary: "How could you have married such an idiot?"
Don't stand next to him when he's on the phone with his ex, making faces and sticking your finger down your throat. Don't write her letters or e-mails, and if she's a crank caller, get caller ID. Fighting about the ex—call it the 'ex hex'—is the equivalent of having a stink bomb thrown into your marriage.
7. "Have you always done that?"
Families have traditions that are meaningful to them. So if your husband and his children insist on watching Hogan's Heroes reruns, putting mayo on hot dogs, collecting rubber bands, or anything else you find distasteful, just keep your mouth shut.
8. "Your room is a pigsty!"
Something's got to give, and neatness should be it. If the situation is desperate and the kids are growing subspecies in their space, get Dad to go in there and organize a cleanup. Life is messy, and it's even messier when you choose a man with children. But remember: It's better to have a man with kids than one without kids who flosses his cat's teeth.
9. "Well, my kids and I..."
If you have kids of your own who live with you and your husband, your stepkids may feel like they're getting the fuzzy end of the lollipop. Mentioning trips, restaurants and the fun stuff you did the weekend they were with their mom feeds the illusion that your children are getting more. Be clear that there are no favorites and everything is even between both sets of kids.