Making impulse purchases

Getting kids to appeal to parents is a time-tested way to increase sales for grocery stores and other retailers. According to reports, advertisers specifically place those items at kids' eye level to get their attention.

Giving in to those impulses won't cost you much at first, Scharr says.

"If your kid is between 3 and 9, that's normally the time when they'll be in the grocery store and say, 'Can I have that candy bar?' And what does a parent want to do? Just get the candy bar and make them happy. It's quick, it's easy, it's not that expensive," Scharr says.

But the cost of adding extra purchases to every shopping trip grows as kids get older, she says. If you've taught them that you're an easy mark, you'll soon face demands to spend money on more expensive items -- dessert at every restaurant, video games, expensive clothing.

How to say "no": Instead of springing for every impulse purchase, try saving money you'd otherwise spend on children's extras in a glass jar to fulfill a specific goal, Aiken says. That way, they can see how saving for something they want can give more satisfaction in the long run, rather than frittering away money on small items.

Splurging on a 'dream school'

College costs have exploded in recent years. Tuition, room and board at a four-year institution averaged $21,189 per year for the 2009-10 school year, according to the National Center for Education Statistics.

In addition, only 40.1% of students graduated within four years of starting college in 2004, according to U.S. News & World Report. So college costs may increase from what parents expect to pay at the start of their child's higher education.

Kids often pick out high-end colleges as their "dream schools" with little regard for cost, expecting parents to pay, says Scharr.

Giving in to those demands, especially when the costs often come at a time when many parents are rushing to save for retirement, can mean that the latter gets short shrift, says Scharr, who adds that she often hears from clients about putting off retirement.

"They say, 'Here I am now at 57 years of age, and I don't have a lot saved up for retirement, but it was because I had to put my kid through college,'" Scharr says.

How to say "no": Look at what you can do financially and communicate that number in clear terms from the get-go.

For example, you could offer to pay tuition for any in-state public university. If the child wants to go to a pricier school, make it clear he or she will have to come up with the difference by applying for scholarships or taking out student loans, Scharr says.

Overspending on weddings

If you doubt whether a child's wedding can be a major drag on your finances, here's a statistic for you: The average American wedding cost $25,631 in 2011, up from $19,581 in 2009, according to a study by The Wedding Report, a market research firm in Tucson, Ariz.

Despite that, many parents still feel obligated to write their children a blank check, even if they're struggling financially. "I have people who have lost their jobs and then want to go pay for their kid's wedding," Scharr says.

Having their wedding costs covered leaves little incentive for children to control costs. That can lead to lasting financial damage to parents for what amounts to a one-day celebration.

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How to say "no": With wedding demands you can't afford, honesty is the best policy. "It's important for parents to be very upfront with their kids," Scharr says. "The kid's going to understand if you explain to him your situation."

Discuss the other pulls on your budget, such as the need to save for retirement or pay down debt, in concrete terms. While your child may still resent the decision, it's more likely that she would rather scale back her wedding plans than cause financial trouble for her parents, Scharr says.

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