Here are three of the week's top pieces of financial advice, gathered from around the web:

Be cautious with crowdfunding
It's wise to be careful when donating to an online crowdfunding campaign, said Consumer Reports. Though instances of outright fraud on platforms such as GoFundMe and Facebook are rare, "they can still happen." A viral feel-good story about a homeless man who handed over his last $20 to buy gas for a stranded New Jersey woman turned out to be a lie, "manufactured to get strangers to donate more than $400,000." You can avoid such scams by donating only to crowdfunders run by people you know. And if a campaign has reached its fundraising goal, "assume it doesn't need more and give elsewhere." Even if organizers say they will donate any excess to charity, remember "that there's no guarantee they will."

Time to trade in old iPhones
The trade-in value of your old iPhone just got "a significant boost" from Apple, said Cameron Faulkner at The Verge. But there's a catch: The increased credit is only available to customers upgrading to the new 2018 iPhone lineup — the XS, XS Max, or XR. The size of your trade-in credit depends on your existing phone: Apple will now pay you $300 for an iPhone 8 (up from $250), $250 for an iPhone 6S Plus (up from $150), and $200 for an iPhone 6 Plus (up from $100). "The amount you're getting probably still isn't equal to what you'd make by selling on Craigslist or elsewhere, but Apple's option is all about convenience." The additional-credit promotion ends Jan. 31.

Pension funds' real estate gamble
Large public retirement funds are taking on "some of the riskiest types of property investments" to help close funding gaps, said Heather Gillers at The Wall Street Journal. These "so-called opportunistic investments" in new properties designed to be sold later for a profit jumped nearly sixfold from 2006 to 2016. Public funds are making these bets because most don't have enough money to pay future benefits owed to police officers, teachers, and more. Estimates of "unfunded promises" range from $1.6 trillion to $4 trillion, and "the funding shortfall is straining taxpayers and putting pension promises in jeopardy." But there's danger in speculation. The real estate holdings of one California fund dropped 48 percent in the 2008 financial crisis. The fund now hopes to have 20 percent of its real estate ­portfolio — about $5.7 ­billion — invested in the riskier properties.