Personal finance from around the Web: Exchange-traded funds are all the rage these days, but are they right for you? Here’s a primer on perks and pitfalls of ETFs. [USA Today] If your teenager is more worried about the latest Twilight movie than her latest bank statement, she might need some credit guidance. Here are some tips to help your teen become credit savvy before the balances accumulate. [Wise Bread] Tipping at least 15% may be customary, but one blogger doesn’t think it’s necessary. He says if you get no service, you should give no tip. [The Simple Dollar] Foreclosure filings fell in January, but California, Florida, Arizona and Nevada are still being hammered. Here’s a look at 10 cities still getting crushed by foreclosures. [Business Insider] Think you know something the market doesn’t? Think again. [Wise Investing] Follow MONEY on Twitter at http://twitter.com/money.