Q: I seem to be starting a small collection of duster-length cardigans, but I don't know how to wear them in the winter. I wear a hip-length jacket and feel pretty silly walking around with a duster hanging down around my calves from under the jacket. What length of coat do I wear with a duster?

A: I'm a lover of below-the-knee dusters myself, and have grappled with the same issue.

Generally speaking, you want your coat length to look intentional: It needs to be long enough to cover all of your layers or so short that it's clear you're not trying to cover them at all. Think a knee-length coat to accommodate a hip-length sweater, or a cropped jacket worn over a maxi-dress. But a duster or long jacket hanging out beneath a shorter coat looks quite odd.

So you're left with two choices: Invest in a maxi-coat or do some creative tucking. So long as you don't risk turning your duster into a wrinkly mess, you can fold the bottom half up toward your body and tuck it inside your shorter jacket. Then when you get inside and remove your jacket, just let it fall down naturally again. No one will be the wiser.

Q: How do you know when to donate something?

A: A great question, and one with two possible meanings.

How do you know when to donate something to best serve the recipient charity? Most thrift stores' sales calendars run a bit behind traditional retail calendars, which means that while spring clothes start showing up at mall stores in January, they turn up on the thrift racks in February and March. So you can definitely donate old winter coats, snow boots and heavy sweaters now — but by April, you'll be handing over merchandise that the charity won't be able to sell for six months or more. Likewise, donating a bathing suit or sun hat in November isn't the best plan. The urge to jettison purged-out clothes can be strong, but try to donate in alignment with the current season.

How do you know when to donate something to best serve your personal style? Naturally, the answer will vary widely from person to person. Some experts recommend a time limit — donate anything that hasn't been worn in six months — but I feel like that can be a bit rigid. Because trends and personal preferences ebb and flow, mass donations based on time unworn can result in donator's remorse. Instead, ask yourself these questions: Does this fit my body right now, as it is? Do I love wearing it and/or love how it looks on me? Is it useful within my wardrobe? Answer "no" to any of these questions, and the item can be passed along.

Q: I just bought a knit skirt and tank top by St. John that were on sale at a consignment shop. Part of me feels like St. John is an old-lady brand, but part of me knows they're classic and well-made and can be workhorse staples. How can I mix them into my wardrobe?

A: St. John and similarly old-school, venerable brands can look a bit stodgy on the hanger, but just about anything can look of-the-moment if styled appropriately. Mix in contemporary or edgy shapes and styles such as slim-ankle pants, moto jackets or distressed jeans, then add modern accents such as bold bib necklaces, ankle boots, patterned hosiery or blanket scarves. Mixing classic and new will create balance.

Also be mindful of fit. Brands that skew older can be bulky and boxy, so offset that volume with slimness elsewhere in your outfit.

Sally McGraw is a Minneapolis-based personal stylist and creator of the Already Pretty (alreadypretty.com) blog. Her fashion advice appears on this page once a month. Send questions to tellus@startribune.com.