While inside IKEA, be as courteous as you would in any other public place. If you're shopping with family and friends, keep your voice down and watch your language. If you're shopping with young children in tow, make sure they're well-behaved and well-rested. If you need to make a phone call to confirm which color curtains your spouse wanted, step off the path, find a secluded place to dial and keep the call short. And no matter how ridiculous the people around you get, remember that it's bad form to snap pictures and video of others.
When you reach the checkout line, don't blitz toward the Swedish food market without paying, and don't save a place in line for anyone who's paying separately from you. When it's your turn to pay, put your phone away: Yammering away is disrespectful to the cashier scanning your purchases and the customers behind you. Before you leave, return your cart. And remember the basics: Say please and thank you, and remember to smile.