When you ask financial and real estate professionals about the best use of a home equity loan or line of credit, the top answer is pretty consistent:

Put it back into the house.

You just can't go wrong with using that money to make your home bigger, nicer and more valuable.

That doesn't mean every dollar you spend will add a dollar to the value to your home.

It won't.

Labor and material costs have continued to rise substantially over the past couple of years, making almost every project more expensive.

Home prices are now falling in most of the country.

You'll actually recoup less of what you spend on home improvements than you would have last year, when everything housing-market-related was tanking.

But the return still isn't shabby: 70 cents of every dollar you spend improving your home will increase its value.

And the other 30 cents? A reasonable cost for improving your quality of living.

That's why Harvard University's Joint Center for Housing Studies projects that homeowners will spend $175.6 billion on improvements in 2008 when the totals come in. That's the same as in 2007.

While the prices for home improvements have risen again, the recoup value has declined to its lowest levels in five years, according to Remodeling Magazine and the National Association of Realtors.

But it's still important to put your money into projects that bring the most value to your home.

To find out which projects do, we went straight to the mother lode of data -- the annual cost-versus-value home improvement survey by Remodeling Magazine and the National Association of Realtors, which aggregates information from 60 cities.

We used the data to create Interest.com's list of the 10 best home improvements, based strictly on the percentage of the cost recouped at resale.

We pulled out variations on the same themes, such as one kitchen remodeling project instead of minor, midrange and upscale kitchen renovations, which the annual survey breaks out in great detail. In those cases, we gave you the version that produced the highest rate of return.

Our Top 10 home improvement projects, with the national average for cost, resale value and the percentage of the cost that was recouped, are:

No. 1. Upscale siding replacement costs $13,212 and adds $11,633 to your home's value, or 88.1% of the cost.

No. 2. Adding a wooden deck costs $10,347 and adds $8,835 in value, 85.4% of the cost.

No. 3. Minor kitchen remodeling costs $21,185 and adds $17,576 in value, 83% of the cost.

No. 4. Replacing windows with midrange wood windows costs $11,384 and adds $9,241 in value, 81.2% of the cost.

No. 5. Midrange bathroom remodeling costs $15,789 and adds $12,366 in value, 78.3% of the cost.

No. 6. Renovating an attic into a bedroom costs $46,691 and adds $35,771 in value, 76.6% of the cost.

No. 7.Remodeling the basement costs $59,435 and adds $44,661 in value, 75.1% of the cost.

No. 8. Adding a second story costs $139,297 and adds $103,010 in value, 73.9% of the cost.

No. 9. Adding a garage costs $53,897 and adds $37,461 in value, 69.5% of the cost.

No. 10. Adding an upscale bathroom costs $73,145 and adds $50,442 in value, 69% of the cost.

A minor facelift would include things such as replacing faucets, adding new flooring, new wallpaper or tile, new towel bar and toilet paper holder, maybe new doors for the shower.

Midrange remodeling adds new vanities and countertops, mirrors, medicine chest and maybe pulling the toilet and doing a new tub surround.

A midrange addition involves building a new bathroom with moderately priced fixtures, such as $165 for a solid-surface countertop with built-in sink as opposed to $500 for a custom-ordered sink that you would expect in a luxury addition.

If the prices seem a little more than you expected, there are several reasons:

Averaging can skew costs higher than taking the mean of all costs. Let's say, for example, three people remodeled their kitchens at a cost of $10,000, $15,000 and $100,000. The mean price would be $15,000 because half of the projects cost more and half cost less. But the average would be $41,666.

The prices include professional labor, which is about 30% of the cost.

There are substantial regional variations in home values, materials and labor costs.

So, how do you decide which project to do and how far to go?

The old maxim of "If a little is good, a lot must be better" does not always apply in the world of real estate.

If the goal of your project is to increase the value of your home for resale, your project needs to reflect the neighborhood.

It's completely within the realm of possibility to spend six figures on a kitchen renovation, but unless you live in a neighborhood of million-dollar houses, you'll want to scale things down a bit.

The same goes with bedroom and bathroom counts. If your neighborhood is chockfull of three-bedroom, two-bath houses and your house only has one bathroom, you're at a serious disadvantage on the resale market. Adding on a bathroom would make a big difference.

Then, you have to consider all the costs involved with a renovation. A swimming pool is the perfect example.

Building the pool is just the beginning of the expense. The same is true of adding on a family room or remodeling a basement or attic. Not only do you have the structural costs, you also will need to furnish those spaces and heat and cool them year-round. So add those costs into your budget.

Finally, some decisions are made with the heart as much as the head. Maybe you've always wanted a gourmet kitchen, or a trilevel deck with a hot tub and an outdoor kitchen, or a home theater with enough space to have your own rock concert.

You have every intention of living in this house for the rest of your life, you know you'll never get the money out of it that you put into it and you don't care. If you can afford it, knock yourself out. It's your house, your money and your life.

Go for it.

By Darci Smith

Interest.com contributing editors

Have a question about your finances? Ask us at editors@interest.com