NEW YORK (CNN/Money) - What's the quickest way for a retailer to shoo away potential customers? Believe it or not, it's not necessarily with prices but with bad customer service.

Consider this: If you're not typically a high-end shopper, but you wander into a luxury store either by accident or by design, a welcoming staff that greets you and discreetly offers assistance may coax you into buying an item or two, and may even make you feel good about it.

On the other hand, if you're watched like a hawk from the moment you arrive and spoken to rudely -- or are blatantly ignored -- there's little chance you'll fork over your hard-earned dollars, no matter how much you love their stuff.

"Obviously price is key to determining where people choose to shop. But after that, it's customer service," said Phil Rist, vice president of strategy for market research firm BIGresearch.

With too many retailers chasing too few consumer dollars, Rist says, merchants can get a leg up on the competition, if they learn to court the customer in simple ways.

He lists a helpful and polite staff, and well-organized and clean stores, as desirable attributes that can go a long way in winning over shoppers.

"Shopping is a sensory experience," said Rist. "People are subconsciously recording things like the layout of the store, the lighting, whether the aisles are overflowing, whether the prices are clearly indicated and how easy or difficult it is to find a product every time you visit a store."

In its latest ranking of retailers, BIGresearch evaluated some of the nation's largest chains in terms of the appearance of their stores and the behavior of the sales staff.

In a survey of 8,701 consumers between June 1 to June 4, discounters Wal-mart (WMT: Research, Estimates) and Target (TGT: Research, Estimates) took the top two slots in a ranking of top 20 retailers with the most courteous employees.

Home improvement leaders Home Depot (HD: Research, Estimates) andLowe's (LOW: Research, Estimates) followed at third and fourth, respectively. Some factors that annoyed people the most, even prompting them to switch to another store, were rude behavior, salespeople who were unfriendly or weren't around to help and staff that wasn't knowledgeable about the store or the products.

High-end retailer Nordstrom (JWN: Research, Estimates), wholesale club Sam's Club and Costco (COST: Research, Estimates) landed in the top 20, but near the bottom of the list.

When BIGResearch took the size of the retailer out of the equation and viewed each retailer as if they have the same size customer base, it found that Nordstrom topped the list as having the best customer service, followed by Wal-Mart, discount chain Meijer and grocery chain Safeway (SWY: Research, Estimates).

Rist of BIGresearch said the second methodology gives retailers a level playing field, removing Wal-Mart's inordinate influence on the ranking.

Home Depot and department store chains J.C. Penney and Sears (S: Research, Estimates) appeared at the bottom-half of the list.

In a separate survey, BIGresearch polled 9,252 consumers from July 1 to July 9, asking which stores they found to be the best and worst in merchandising.

Nordstrom took the top slot followed by Best Buy (BBY: Research, Estimates) and Target. Among the laggards were Dollar General (DG: Research, Estimates) and Kmart (KMART: Research, Estimates).

"You can't expect a store to look absolutely perfect, but the one that surprised me was Kmart," said Rist. "Kmart isn't a flea market-type store. It needs to do a much better job in making its store more attractive to customers."

With online shopping nibbling away at the overall $900 billion retail pie, market research firm Vividence recently came out with its first-ever ranking of 20 top online merchants, grading them on customer experience, visual appeal, efficiency of the Web site's search engine and overall ease of use.

"We looked at 20 leading online retailers from multiple categories," said Liz Edison, director of syndicated research with Vividence. "We tracked consumers as they navigated the different sites and measured their experience using a number of benchmarks such as a Web site's success or failure at converting browsers into future buyers."

The results of the survey of 2,000 consumers from July 9 to July 16 awarded Amazon.com (AMZN: Research, Estimates) top honors as the best place to shop online.

"The visual appeal of Amazon.com really stood out," said Edison. "The site offers 360-degree viewing of products and very detailed descriptions. The one-click checkout process is efficient and easy to navigate, and its search engine is pretty fast."

Barnesandnoble.com, eBay (EBAY: Research, Estimates) and electronic retailer Circuit City (CC: Research, Estimates)'s online stores also scored high marks. Best Buy, J.C. Penney (JCP: Research, Estimates), Nordstrom and Costco scored lower on the list.

"Costco's search engine is poorly designed and the Web site overall doesn't engage the user," said Edison. "Best Buy's offline stores may perform better, but online the retailer lost out to Circuit City in terms of customer support, visual appeal and the purchase process."

Wal-Mart also ranked in the bottom tier (14th on the list). The Vividence survey found the world's biggest retailer had one of the poorest buyer conversion rates, where the site scored low marks in getting people to buy an item online rather than just browsing for products.

The study said consumers were particularly frustrated with the design and organization of Wal-Mart's Web site, as well as their ability to browse and search for products.