The creative director at Marni on male vanity, the importance of modern suits, and the perils of ugly shoes. 

1. A man has to discover his own taste and then base his sartorial decisions on that-you shouldn’t buy something because you saw it on TV. You need to feel at ease in your clothes or you risk being a bit ridiculous.

2. I like a guy in a suit that’s cut a little smaller-slightly shorter, with smaller lapels. Inside, the jacket should have beautiful finishing that only the guy wearing it notices.

3. Italian men are very vain, even if they won’t admit it. They care about their style.

4. Not everyone looks good in a tuxedo. It’s important to look at proportions and find one that fits you well.

5. Shoes define the kind of man you are. They should never be too trendy or showy but lean toward the classic. There are a lot of ugly shoes out there, and they can ruin even the most sophisticated attire.

6. A little bit of chivalry always makes a woman happy. You shouldn’t exaggerate, but I do like it when a man holds the door open for me. I think, Okay, this guy has manners and knows how to comport himself.

7. When it comes to wearing color, you need to be a bit careful-a bit more traditional. A man should look sophisticated and refined, and color can sometimes get in the way. You have to be moderate.

8. Men can carry bags as long as they are masculine, like a tote or an attach© case. Look for a sturdy canvas or handsome leather one, maybe with a raw finish. A bag should be functional and practical.

9. Clothes don’t necessarily render a man sexy-his attitude and his nature do. For me, someone who is not classically handsome but has a lot of charm is more attractive than a really good-looking guy with no personality.

10. My husband’s style is classic, but he’ll occasionally wear a Marni sweater or sneakers with a suit or try a jacket that’s slightly shorter, and it works for him. My son is more daring. The most important thing is to be yourself.

Check out these top stories from Details:
FOLLOW THE RULES: LUCAS OSSENDRIJVER
Lanvin’s inventive men’s designer on the merits of sneakers, the tackiness of logos, and why you should invest in a mismatched suit.
FOLLOW THE RULES: V‰RONIQUE NICHANIAN
The menswear designer at Herm¨s on the myth of French style, avoiding trends, and why you can never have too much cashmere.
FOLLOW THE RULES: PAUL SMITH
The sharp British designer on poorly dressed Londoners, Daniel Day-Lewis, and when you should lose the bow tie.