I absolutely loved my time as a foster mother and took in dozens of troubled pre-teens and teens in the years I did it. Some stayed a few days and others I had for over a year. Along the way, I learned a few things about making them feel welcome and comfortable in their new digs.
Spend a little time interviewing them
Ask them questions about their hopes and dreams and then talk about your expectations. Most people love to talk about themselves and this is a way to show them right off the bat that you care about them and not just the stipend. There are a lot of folks that work for that reason and most foster kids are aware of that. Show them that you really want them there and care about them as a person.
Give them a grand tour
Many foster kids come into care with fears and anxieties. They are in survivor mode and like for everything to be out in the open. By showing them not only the essentials like bathroom, laundry room, family room, etc., but also the attics, closets, basements, and other uncommon spaces, you are showing them that you trust them and that they can trust you.
Give them some control over their personal space
Allow them to put their own creature comforts into their personal space: posters, family pictures, stuffed toys, books, etc.
Have the house rules in writing
Present them with the rules of the house in writing so that there are no fumbles or fouls later on. Talk them through and ask if they have any questions. Make certain that they know that these apply to everyone and not just them.
Have the consequences worked out and present them as well
If you discuss the consequences to bad behavior beforehand, you can avoid, "Are you kidding me?" if and when they happen. Consequences should be no more lenient or severe than they are with your own children if you have them.
Every household runs more smoothly if there is a distribution of responsibility. By giving them regular chores, just as you do your own family, they will feel like they are one of you and contributing to the welfare of the home. If you treat them like a guest and constantly say, "Oh, no, that's alright, we can do this," you are actually excluding them from being a part of the whole.
Question and answer time
Consider having the family all sit down and allow questions and answers — a kind of get-to-know-you. Avoid delving into things that are too personal. They will enjoy finding out about their new family and telling the new family about themselves.
A fresh start is a wonderful opportunity, so try not to allow their past to influence you in your decision making as far as you can. Should they mess up, don't use phrases like, "I was afraid this would happen!" or "They warned me about this!" Treat it as if it had never happened before and make sure that you firmly but gently tell them you expect better of them.
Set aside one night a week where you eliminate outside influences: cell phones, iPads, television, phone calls, computers, etc. Just have fun as a family and consider holding a family pow-wow or council to go over things. Allow each family member to air their concerns and listen with an open mind. Then play parlor games and have snacks. This is a wonderful opportunity to bond and let them know that they are more important than work, a favorite TV show or Facebook.
Fostering children is a great opportunity. There were kids I hated to let go of and some I couldn't wait to, but I would do it again in a heartbeat. Just remember that if you do this, you are inviting them to be one of you for a period of time and that the same blessings, opportunities and discipline apply to them as to your own.