Group-buying coupons are everywhere, from the monolithic Groupon to sites that service just one or two cities. Some of the coolest coupons are for stuff you never imagined doing, like skydiving. Others offer deals on movie tickets and—most popularly—spa services.

Groupon, which recently was heavily courted by Google, is coping with competition from Living Social, which is backed by Facebook recently launched its own daily-deal program for five markets, and rebuffed Google is now going at it alone in several test markets. And, most recently Markdown launched offering daily deals, similar in format to Groupon.

With all this competition, many offers seem irresistible, but how do you know when it's truly a good deal? Here are eight ways to get the most out of your deal-of-the-day.

1. Location, location, location

While the larger group-buying companies have expanded into smaller cities, many deals are still offered only for metropolitan areas. Before clicking on the offer, consider whether you'll really make that long drive, particularly when taking into account the expiration date.

2. Travel destinations

On the other hand, you don't always have to live near a deal location to use the coupon. Check out potential vouchers for places you'll visit on your next vacation. You might want to wait, however, until all your plans have been confirmed before closing the deal, but you can certainly save anywhere from 50 to 70 percent by taking advantage of such group offers for restaurants, spa services, entertainment, and even museum admissions.

3. Combine offers

Put together your own special deal by applying coupons and discounted gift cards to those deal-of-the-day vouchers.

4. Is it really a deal?

If you're going out of your way to patronize a new business, check their website to see if they extend any similar offers on an everyday basis. You'll also want to compare prices at businesses you prefer to regularly patronize to figure out if the deal is really worthwhile.

5. Restaurant coupon comparisons

A lot of coupon offers involve restaurant meals at a discount. Some require you buy two meals to receive the deal of the day. Before you buy always review the rules and restrictions of the vouchers and look for restaurant coupons on other sites and see if you can beat the offer without paying anything.

6. Figure in the tip

Group-buying deals for services don't include the amount of money you'll spend on a tip. You'll need to tip 15 to 20 percent on the full cost of the service, not the reduced amount you paid so keep this in mind when considering purchasing the offer.

7. Plan ahead for presents

Some offers have extended expiration dates and would make great gifts for just about any occasion. You'll have to suit the gift to the recipient, however, free spa services or dinner in an upscale restaurant make ideal presents to just about any adult celebrating a special event.

8. Resale value

People occasionally sell vouchers on sites like Lifesta to others for a profit once the deal is no longer available. This works well if you're the one selling, but you might want to check the original price if you're the one buying.

As popularity of deal-of-the-day sites is rising, share these 8 tips with your friends so they too can get the most out of daily deals.

Consumer Savings Expert Andrea Woroch has been featured on NBC's Today Show, FOX & Friends, MSNBC, ABC News NOW, and many more.