Manny Miller admits he was ignoring the conventional wisdom when he decided to move the family fur business into new quarters downtown at 13th and G Streets NW.

"People would ask my father if I knew what I was doing," he said. "They thought we ought to go to Connecticut Avenue or Chevy Chase."

There were doubters too when Totally Tennis took over a rival in Rockville and announced it planned three more giant tennis stores in Washington.

"It's an industry that's peaked out," acknowledged vice president Phil Glassman. "We think we can make it because we are pros."

And Stanley Mills said employment agency professionals scoffed when he announced he as going to introduce the concept of multiple listings to the business.

But a half dozen agencies have signed up and more than a hundred job seekers now have their qualifications listed like houses in the real estate market.

Miller Glassman and Mills all contend there's money to be made by swimming upstream, bucking the trend, carrying coals to Newscastle.

"I think we're really the new pioneers of downtown," said mIller said yesterday, after writing up a sales ticket for a full length fur coat. His furs start at $600 and quickly reach more than 10 times that amount.

"Business is good for us here," he said in an interview at the still unfinished upstairs office of the store that opened Monday at 1304 G Street. It's twice as big as the one around the corner: Miller and his father are betting a vault full of pelts that business will be better.

Isador Miller opened his first fur shop downtown in 1921. "There were more than a dozen furriers here then; now we are the only one," he recalled yesterday, tracing the progression through four locations, riots and subway construction.

The while customers, who disappeared after 1968, are coming back now and represent nearly half the business. The subway holes are healed, and young Miller talks confidently about the neighborhood.

"Motioning toward the parking lot across the street and urban renewal targets around the corner, he said. "One of these days the developers will start and these bukldings will go like dominoes. There will be office buildings on those parking lots."

"We feel our store is going to grow with them. We think we know what we're doing."

Stanley Mills thinks he knows what he's doing with his mutliple-listing employment service too. He calls it Emplolbank and it works this way.

A job seeker signs up with Mills fills oin the usual forms, supplies a resume and pays a modest fee. Emplolbank not only matches the applicant against jobs listed in its own files, it sends the individual to more than a dozen other agencies.

"Employment agencies always have jobs they can't fill," he said. "This gives them a bigger field of applicants."

The multiple listing concept has never made it in the employment agency business before, because agencies jealously guard their job listings, which are their source of profits.

Sharing people is a little easier, especially since th eagencies spilt the commission, just as on real estate listings.

Mills said he got into the generally moribund employment agency business with a different idea - video taped interviews, three-minute vignettes that would give employers a quick look at applicants.

That didn't fly, he admits, but an industry so steeped in archaic methods has to be ripe for innovation, so he's trying Emplobank.

The tennis business isn't stale, it's overheated, said Phil Glassman, vice president of Totally Tennis, a Baltimore-based company that opened the first of four planned Washington stores last Saturday.

The growth of the tennis trade probably was fastest last year and as it slowly a shake-out is occuring. Totally Tennis took over the former Tennis World store across from Congressional Plaza on Rockville Pike.

Tennis World was, "the recognized giant" among Washington Tennis retailers. Totally Tennis is three times as big, said Lenny Schloss, president of the company, which projects a $1.7 million volume this year.

That's exactly opposite the usual approach of tennis boutiques , "Our outlook is that boutiques are a dime a dozen," said Glassman. "We consider ourselves a tennis department store.

"We aim to be able to serve the entire tennis playing world." That means offering rackets from $9 to $200 and warm-up suits ranging from $170 high fashion to $19 discount store versions.

But why does he think Totally Tennis can make it where others are failing?

"I have to say this so it doesn't sound nasty," answered Glassman. "We are pros (he's a former playing pro) but we are retailers. We know the business. In an industry that's peaking, we can continue to grow."