Last week I had the nicest e-mail exchange with Ariella, who has a specific question about what to wear to work.

I am wondering if you have business-wear advice for plus-size women. I am a lawyer, and the dress at my job is business casual, so I can basically wear whatever I like. The other lawyers have been known to wear holey teeshirts, for example (they are men).

I am a size 16-18, and it is damn hard to find attractive, well-fitting clothes for women who are overweight. I generally wear black pants with a colored shirt, but there is absolutely no style to what I wear. And I would love some help, but I just don’t know where to go. I dislike the styles (trendy) at Lane Bryant, and the stores here don’t carry my size, so I usually order off the web. This is highly inefficient, so I feel like I usually look frumpy, fat and unstylish at my job.

The main problem I have (as I see it) is that my style is more traditional and preppy than the plus-size women’s wear out there. Lane Bryant and Torrid tend to have clothing that is “trendy,” and I also feel that a lot of it is not flattering on larger women. It’s my firm belief that you can’t just take styles that fit/flatter thinner people and put them on fat women to make them stylish. For me, at least, I need a lot of structure because of my weight.

Ariella already has a good sense of her own style–she knows what she wants, and what she doesn’t want–and she is dead on in her assessment that taking a look and recreating it in a larger size doesn’t do a plus size woman any favors. Let’s talk about what she needs and how she can up the style factor of her current closet.

To build a functional work wardrobe, no matter what your size, start with classic basics. Ariella needs a terrific pair of black pants, with a flat front and wide legs (the leg should fall straight from the widest part of the hip). She also wants to look for a straight skirt (again, one that falls straight from the widest part of the hip). She wants to steer clear of tapered pencil skirts, which will make her look like an ice cream cone, and be cautious of very wide A line skirts, which will give her more volume across the bottom.

She can pair them with a wrap sweater or blouse, which will emphasize her curves, or a sweater with an asymmetrical or V neckline, which will draw attention to her face. Button front shirts are also fantastic, as long as they fit properly through both the shoulders AND the bust. The placket should lay flat and not gape. If Ariella would prefer not to tuck the shirt in, she should look for a style that tapers at the waist, or have her shirts tailored to bring them in at the waistline.

Ariella can put a jacket over the button front shirt; if she leaves the collar out, over the jacket collar, this will give her more visual interest near her face and create a nice V neckline. But be SURE the jacket fits properly–she should be able to button it, even if she will NEVER wear it that way. A jacket that fits in the shoulders but is too slim to button does NOT fit properly, and it will make you look bigger through the chest. By the same token, a jacket that buttons properly but is too big in the shoulders or through the body will make you look bigger through the midsection. Buy the jacket that fits through the chest and have the rest altered.

For her casual office, Ariella might want to go with a denim or leather blazer, rather than a suit jacket. Denim and leather are heavier fabrics, which will give her the structure she’s looking for; they are also traditionally more casual fabrics, so she won’t seem overdressed. She should steer clear of chest pockets, or flap pockets of any sort. The jacket’s shape can be either a one-button (which will help define Ariella’s waistline) or a boxier shape that hits at the high hip.

When you wear a plus size, look for lighter-weight fabrics in cuts that fall close to the body; this will play up curves and highlight your shape. Look also for pieces with structure, rather than floppy pieces that just lay there. Above all, resist the urge to buy big just because you ARE big; no matter what your size, buy ONLY pieces that fit correctly, or have thing tailored.

What can Ariella do to make her basic Preppy wardrobe more individual and stylish? She can think carefully about details: rather than a button front shirt, go with a wrap shirt; instead of a crew neck sweater, she can look for a sweater with some detailing at the neckline. She can also think about incorporating one or two more trendy pieces into her basic wardrobe, either as accessories (a great metallic bag or animal print shoe) or in a carefully selected wardrobing piece (a 50s inspired suit jacket for fall). She can use jewelry (chunky necklaces or a wide cuff bracelet) to give her basics character. Because Ariella is a bigger woman, she wants to be sure that her accessories are properly sized; she should go for a substantial bag and bigger jewelry, not a wee clutch or tiny pearl stud earrings.

Those are the basics, but now I need YOUR help: Ariella also wants to know where to shop. I want to send her to the best possible places, but honestly, I don’t know where those might be. Where do YOU shop for great plus-size clothing? Are there Internet sites with particularly good return policies? Or with really great customer service? Where are you having the best luck finding great things to wear to the office?