The time of year has come when Beverly Hills floor-covering companies go on red-carpet alert, and when a movie starlet's thoughts turn from clothes to ... well, clothes.

Joan Rivers morphs from the most annoying comedian on the E! network into the most feared woman in Hollywood, which can only mean one thing — awards show season has begun. 

For the next two months, we all become armchair Mr. Blackwells, as we cheer and jeer our favorite stars' formalwear choices. 

Dress dissing is much more fun if you know what to watch for from one red carpet to the next. Each awards show has its own sartorial "personality" — from the anything-goes Independent Spirit Awards to the ultra-haute Oscars. What works at the almost-Oscar Golden Globes, might not cut it at the experimental Screen Actors Guild Awards, and so forth. 

To help you sort out the rules, The Post has assembled this list of awards-show dressing do's and don'ts, tailored to each broadcast. By the way, here's a caveat that goes for all of them: Never, ever be caught wearing the same dress twice. 

GRAMMY AWARDS (Wed., Feb. 21): 

 A crowd gathered in a space named after an office supply store can't be expected to be all that clothes-wise. The Staples Center wasn't exactly chic central last year; don't hold your breath this time around. 

Cut country music stars some slack. Everyone in Nashville (save Faith Hill) seems to think the whole jeans-with-tux-tails is still cute after all these years. Bless their hearts: They don't know any better. Take it from a Tennesseean. So don't make fun of anyone wearing a cowboy hat - unless it's Madonna. Her lame cowgirl look deserves derision.

It's an unspoken rule that attendees must not dress in anything that a 14-year-old would not find attractive. A Grammy outfit's just not a Grammy outfit unless it would cause your mother to pass out.

Nine out of 10 women will be wearing (very skimpy) Versace. Nowhere on earth can you find more of the Italian fashion house's clothes than the Grammys — except maybe Elton John's closet.

Every reasonably stacked woman who has a shot at scoring camera time will try to out-do last year's awe-inspiring show of decolletage by Jennifer Lopez. Those who don't take on La Lopez will attempt to show more belly skin than Christina and Britney combined.

SCREEN ACTORS GUILD AWARDS (Sunday, March 11)

This is the last chance for an actress to "experiment" with her looks before the Big Os. You know Lara Flynn Boyle would never step foot on the red carpet leading up to the Dorothy Chandler Auditorium in an Afro, as she did at last year's SAG ceremony. I

INDEPENDENT SPIRIT AWARDS (Saturday, March 24)

Don't discount the Independent Spirit Awards' fashion influence just because the show's held in a tent. If you have well-dressed stars, fashion watchers will take notice. Last year's ISA presentation got a ton of free publicity, thanks to Chloe Sevigny. Each week, it seemed, a picture of the actress in the Celine brown paisley print halter dress she wore to the awards appeared in a different fashion magazine. Beat that!

Guys shouldn't feel the need to wear a tie to the lowbrow-and-proud-of-it ISAs. The powers that be there didn't hold it against award winner Hilary Swank when her escort, hubby Chad Lowe, showed up with a loose collar.

OSCARS (Sunday, March 25) 

Girls should look like, well, girls. We're sure American beauty Mena Suvari was going for a vintage Hollywood star look at last year's Oscars in a silver beaded Escada column dress and beehive 'do. But instead of looking like a silver-screen siren, she came off looking like someone's grandmother. In a town so obsessed with looking young, you'd think everyone would try to look 19 instead of 91.

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