If you venture abroad this summer, follow these tips from Susan Stellin, author of How to Travel Practically Anywhere (Houghton Mifflin, $16, www.amazon.com): Register with the State Department (travelregistration.state.gov). Check the expiration on your passport (some countries won’t let you in if it is due to expire in the next six months). Call your credit-card issuer to advise it not to put a hold on your account due to “unusual” spending. And consider getting travel insurance if your health insurance won’t cover you outside the United States.