Over the years, I've seen many ways that people sabotage their own finances. I rounded up some of the most common in "7 surefire ways to stay poor," which just posted on MSN.

(Personally, I would have preferred they used the word "broke" in the headline, rather than "poor." Poverty has many causes and roots far deeper than anything I can address in a column, while being broke is something we bring on ourselves.)

If I had to pick one of the 7 that causes the most trouble, it would be failure to have an emergency fund. Even a few hundred dollars can make the difference between handling an emergency and slipping down the slope into more debt.

The IRS just boosted the business mileage deduction by eight cents a mile, to 58.5 cents from 50.5 cents. The change applies for the last half of 2008.

The tax agency usually adjusts the mileage deduction once a year to reflect the average costs of operating a car, but soaring gas prices prompted a mid-year adjustment.

Even if you don't write off your mileage for business, the IRS figure is a helpful proxy when you're trying to figure out how much your car costs to operate once fuel, maintenance, insurance and depreciation costs are taken into account.

So the next time you take a trip, whether it's to the grocery store or over the hill to Grandma's house, calculate the cost. A 10-mile drive, for example, is like forking over $5.85. One hundred miles? $58.50. (Of course, if that's too much math, use a proxy for the proxy: Cut the mileage in half and add 10%. Your 100 mile trip will turn into $50 plus $10, or $60--close enough.)

That little bit of math will help you determine which journeys are worthwhile and which should be combined with other errands or avoided altogether.

Bills.com offers a quick little financial quiz to help you judge your overall financial health.

The quiz takes just a couple of minutes to complete and asks questions about five key areas of your finances: credit, debt, budgeting, wealth and "life plan," which includes career and estate planning.

This isn't exactly a substitute for a sit-down with a fee-only financial planner, and I have a few nitpicks with some of the questions (such as the notion your credit's okay if you're paying your credit cards in full every month, since your credit scores may still show you as "maxed out" if you're using substantially all of your credit line).

But overall it's a good way to see if you've got a good general handle on your finances and what areas might need improvement.

I'm co-hosting a savings contest with FNBO Direct, the online arm of 150-year-old First National Bank of Omaha.

To enter, you submit a one-minute video explaining what you're saving for and why. FNBO Direct will choose five folks from the entries to be contestants in its Pay Yourself First Challenge. Each will get a dollar-for-dollar match of what they save during the six-month contest, up to $5,000, and the grand prize winner will get a spa vacation.

You can find out more, including the official rules and how to enter, at PYFChallenge.com.

ShopSmart recently singled out the best store-branded credit cards--along with a few you should skip.

(If you haven't run across it yet, ShopSmart is a relatively new magazine from Consumers Union and it's worth checking out. Think Real Simple meets Consumer Reports: nice design, fun to read and plenty of worthwhile advice and tips inside.)

Some highlights:

The best cash-back store cards include Costco American Express (1% on every dollar spent at Costco or other retailers, 2% on airline, hotel charges, rental cars and cruises, and 3% on restaurants and gas stations) and Wal-Mart Discover Card (0.25% to 1% of every dollar you spend, with the rebates increasing the more you spend).

The best for loyal customers include Ann Taylor Visa (4% on every dollar spent at Ann Taylor locations and anntaylor.com, and 1% spent elsewhere); Barnes & Noble MasterCard (5% back on most store items, plus one point for each dollar charged elsewhere. 2,500 points earn a $25 gift certificate); Bloomingdale’s Visa (3% reward for every dollar spent in the store and 1% for purchases made elsewhere. Requires $1,000 in Bloomie’s purchases annually); Macy’s Visa (up to a 3% reward for every dollar spent at Macy’s, and 1% on purchases elsewhere, good toward gift certificates after you spend $500) and Target Visa (one point per dollar spent at Target and one point per $2 spent elsewhere; 1,000 points earn you 10% off one day of purchases.

Some to skip: Abercrombie & Fitch, Crate & Barrel and Lowe’s, which have no rewards programs.

But if you're serious about rewards (and don't carry credit card balances), you'll also want to check beyond the universe of store cards. Starwood American Express, for example, is a great card for those who want travel rewards, and American Express Blue Cash is at the top of my list for cash back rebates. For more, check out my MSN column, "The 15 most rewarding credit cards."

If you've got a sunny patch of lawn or even a patio, you can grow vegetables to cut your food bill and please your palate.

Two of the easiest to grow: tomatoes and sweet peppers. (Sweet peppers are one of the five foods that shot up the most in price in the past year, as I wrote in "High food prices? Here's how to save.")

If you've never grown anything, start small and don't over-invest in supplies. If you're patio gardening, you'll need a cheap pot or two, potting soil, seedings, stakes and maybe a little Miracle Grow. Otherwise, you'll need just the seedlings, stakes and Miracle Grow.

You can buy stakes or wire cages, or make your own with four three-foot sticks looped with twine.

Put a note on your calendar to check and water the plants every few days. If you're plagued with slugs or snails, a simple beer trap will get 'em--just bury a plastic bowl near the plants so the top is level with the ground, and fill it with cheap beer. The critters will be attracted by the smell and will go willingly to their doom.

If you're still unclear why you need to get copies of your FICO scores before applying for a big loan, read "Lender's goof slams credit scores."

Sallie Mae included the wrong code in a recent download of account information to credit bureau Equifax. The code it applied to customers with graduated payment plans--where you make smaller payments at the start, which later grow--is actually meant to be used on borrowers who haven't kept up with their payments. In other words, Sallie Mae reported up to 1 million of its customers as delinquent, and trashed their Equifax credit scores. Some scores fell more than 100 points, from the "excellent" range to near-subprime.

Someone who pulled a credit report, rather than getting her scores, would have been hard-pressed to detect the little change that made such a difference. The annotation, "arrangements made to make partial payments," was tucked away under "descriptions" in the borrower's Sallie Mae account entry. Elsewhere, everything would look fine; in the summary, the loan would still say "paid as agreed."

Sallie Mae says it has fixed the error and all seems to have returned to normal. But this should serve as a warning. Even though credit reports have become easier to read, don't assume you know what they're saying. Before a major loan, get your FICO scores, so you know what lenders are seeing.