George Kotsiopouloulos knows celebrity style, and he’s sharing it in his new book.

As one of the co-hosts of E!’s “Fashion Police,” Hollywood stylist George Kotsiopoulos pals around with Joan Rivers and dishes on which celebs are haute or not. His new book, “Glamorous by George: The Key to Creating Movie-Star Style” ($20, Abrams Image), details how ordinary women (on ordinary budgets) can take fashion, beauty and party inspiration from starlets both present and past.

The book highlights so many retro styles and 20th-century stars. Why did you get nostalgic?
The past 20 years have just been a rehash of the past 90 years. Every season you’ve got another decade to be inspired by. So it’s good if you decide you’re a 1950s girl who needs more structure. It’s about what’s flattering on your body.

Define movie-star style.
It’s about being elegant and gracious. Movie-star style is not wearing your clothes nine times too small with horrible heels, like “Mob Wives” or whatever.

Why did elegance disappear?
Maybe it was grunge or the advent of the tracksuit. Things just got a little too casual. I’m not saying everyone has to be dressed to the nines all the time. But we know you are not going to yoga right now!

So how can I become elegant?
Tailoring is a big thing. Women think they can buy things off the rack and they’ll fit. Posture and confidence are huge, too.

What garments do we ignore at our peril?
Undergarments, for sure. If you have a fabulous gown and your breasts are sagging to your knees, what’s the point?

Has how we look at celebrity fashions changed?
It’s much more commercialized now, and we now know who designs everything stars wear and where you can buy it.

In the book, you talk about watching “Dynasty” as a kid and being inspired by the glamour. What shows have that vibe now?
The throwback ones like “Mad Men.” And of course, “Sex and the City” was so influential.

Is “American Hustle” going to bring back the 1970s?
I think the 1970s are really going to have a resurgence, but we’ve seen that before. They always come back.

You love vintage clothing. What are the best pieces women can score?
I think evening wear is really fun and it’s usually cheaper than new. Right now I think there are lots of sparkly 1980s jackets out there. Just rip the shoulder pads out, push up the sleeves and wear one with a T-shirt and skinny jeans.

You include a section on entertaining. How should a star party?
When you throw a party, it should feel like an elegant club. Even the dumpiest place looks so chic if you fill it with candles.