If you believe a navy blue blazer is a classic, or—admit it—you’re still wearing a double-breasted suit from the Gordon Gekko era, it’s time for your makeover. And David Becker will happily oblige. The gentleman’s fashionista has been dressing stylish men in the Bay Area and beyond since the early ’80s, when his Versace boutique attracted a roster of rockers, including Eric Clapton, Elton John, Phil Collins, and Rod Stewart. The 1987 opening of Diagonale, one of the first U.S. stores that sold Dolce & Gabbana, sewed up Becker’s reputation as a purveyor of new talent. Now he continues the tradition at the Archive, the three-year-old Union Square shop where he serves as arbiter-in-chief. Becker is easily one of the best-dressed guys in town, but his willingness to share is even more appealing. He freely offers customers his seasoned advice (even via email), so they can look as dapper as he does.

Before a man even steps foot into a store to buy a suit, what should he ask himself? What is his budget and what is his style? If he has $1,000 to spend, he’s wasting his time going into Wilkes Bashford. A hand-tailored suit starts at around $1,300 and goes up to $6,000 or $7,000, depending on the fabric and the amount of handwork. Anything below $1,300 means a lot of the construction is done with fusing and glue, and it won’t have hand-tailoring unless it’s on sale. Check the sale rack at the Archive in July and January. Otherwise, try Macy’s.

What are the details that can help you tell a suit is handmade? About 90 percent of the hand-tailoring is in the collar and lapels. You should be able to see the hand stitches—hundreds or even thousands—that produce a soft roll in the collar and lapels. Less expensive suits with fused lapels are ironed to a crease.

What is a classic style that will last? There is no such thing. “Classic” is a moving target. If you see a guy wearing a suit that combines a loosely cut three-button jacket and pleated, full, high-waisted trousers that he bought in 1998, it looks dated, despite the fact that it looked “classic” when he bought it.

But you’re wearing a three-button jacket! Yes, but it’s shorter in length and more fitted. What also makes it modern are the rectangular suede elbow patches—in this case, they’re unusually large.

What is the suit for the next 5 to 10 years—or at least for the moment? The jacket should have one or two buttons set relatively low, and peaked lapels. The jacket length has gotten shorter; it used to extend to the second knuckle of the thumb and it now ends at the first knuckle. The pants should have a flat front and a slightly tapered cut. High-waisted pants with pleats are pretty much obsolete. Today’s lines are slim and emphasize the body.

Is it true that ties, lapels, and collars have a symbiotic relationship? With the slimming down of the suit, are thin ties also in? Yes, for the average-to-slim guy. For bigger guys, it’s okay to wear a lapel, tie, and collar that are a bit wider, so they look in proportion.

What drives you crazy about the way men dress? American men tend to wear their clothes too big and baggy. It is almost as if they are afraid to show their bodies. I am not certain where it comes from. But my biggest pet peeve is bad shoes.

So, what are some options for a man who wants to look professional, but does not want to—or have to—wear a suit? A sport coat or blazer always looks good. A shirt that is nicely tailored and long-sleeved. Unless you are a golf instructor or a trainer at a gym, I wouldn’t wear a polo or a knit shirt. If you do wear one, it probably looks better to have a blazer on top of it. And remem­ber the slim-cut pants.

What about formal wear? What is “creative black-tie”? That is basically saying you don’t have to wear a tuxedo. It’s fine to wear an evening jacket with a license to mismatch, or put various dressy elements together. I prefer to call it “alternative black-tie.”

I recently went to a creative black-tie event, and many of the men wore a satin or embroidered vest under a tuxedo jacket. They are locked in a time warp. That sounds like Nicole Miller, vintage 1995.

Give me an example of something you’d combine for a black-tie event, creative or not. A Neil Barrett shirt with a printed-on black tie with any kind of formal or dressy black jacket. It’s formal with a sense of humor.

Workplace dress rules about dress got looser for a while. Have you noticed a backlash? Casual Fridays came about because styles were changing, and wearing a suit and tie wasn’t required anymore. Now, the only men wearing suits are those who have to wear them to work, a wedding, or a bar mitzvah. Otherwise, men don’t wear suits if they can possibly avoid them.

What are some alternatives to the casual cliché of khakis and a polo shirt? That is merely replacing one uniform with another. Fashion doesn’t have anything to do with that. I don’t speak the language of Casual Fridays.

I’m afraid to hear what do you think of Silicon Valley style. Dot-commers seem to reject fashion entirely, despite the collective billions they earn. That is the worst-dressed group of individuals you will see in any professional environment. Steve Jobs created a look that works for him: nice glasses, a great T-shirt, and a good pair of jeans. But a lot of people can’t pull that off, so it comes off as sloppy. That crowd really needs help.