Sydney Vincent scrolled through the feeds of her favorite Instagram accounts, envying the sea of artful graffiti, glistening swimming pools and cocktails that looked like they were made to match the perfectly manicured hand in which they were held.

Her stomach sank as she looked at the image she’d just snapped: The ice was quickly melting in her muddy coffee, and the sunlight streaming through the window blurred the already distracting background of the bar where she took the picture.

“I had this image in my head of how I wanted it to look, and I knew what I saw on my iPhone just wasn’t it,” says the 24-year-old Chelsea resident, who created a bicoastal blog, WePerceive.com, with her Portland, Ore.-based pal Kimberlin Glenn. “I wanted to create this beautiful lifestyle destination. But I had no idea where to begin.”

Enter the Instagram consultant. Part photographer and part critic, these experts have become a must-hire for wannabe social-media stars on the photo-sharing site, which has exploded to nearly 400 million active users.

And in an era where one’s personal brand is paramount, 20-somethings say an influential Instagram account nets once-in-a-lifetime opportunities, job offers and experiences.

Vincent paid Louisa Wells, a 23-year-old Upper East Sider who works at a photo studio, to help her upgrade the @we_perceive Instagram feed. Wells has more than 28,000 Instagram followers (@louisa.wells) and charges $150 for an initial consult. “My own Instagram feed grew organically, and what I bring to the table is an artist’s view. I’m able to see the feed as a cohesive whole, and work with individuals to make sure that their photos match their brand,” says Wells.

Once Vincent started following Wells’ advice, she and Glenn saw their likes nearly triple. Now, @we_perceive receives about 100 likes per image, impressive for their 1,200-plus followers.

“Before I thought in terms of one image. What Louisa taught us was the importance of having a color scheme and an aesthetic throughout. Now when I post an image, I think a lot more about how the photo fits into the overall feed,” says Vincent, who believes the investment in coaching was worth the return in terms of visibility, as well as opportunities to collaborate with companies on sponsored posts — such as a recent partnership with athleisure-wear company Sweaty Betty.

Even without an existing brand, millennials say it’s important for individuals to think of themselves as one in order to secure future opportunities.

Erin Cullen, a 23-year-old Noho resident, hired Wells to help promote her personal Instagram page, @erinanncullen. “Our ability to visually tell stories is becoming increasingly important to our creative satisfaction and professional success,” says Cullen, who has a day job working in e-commerce but aspires to become a fashion blogger.

After a few sessions with Wells, Cullen’s followers climbed from the low hundreds to nearly 2,000, and she began netting more brand partnerships: In the past year, she’s landed nearly a dozen with jewelers and fashion boutiques, resulting in free products in exchange for content.

Ashley Adams, 33, a DC-based blogger, worked with NYC-based Instagram coach Lacey Faeh when she wanted to become a fashion influencer with her Instagram handle @chicvilleUSA. While she declined to say how much she paid Faeh — whose rates vary depending on the job — she says her social-media profile has been on a constant upswing since their collaboration.

“I wanted fashion brands and labels to notice me, and I knew, in order to do that, I needed a really strong presence,” says Adams. But what took Adams aback is just how much work keeping up an engaged Instagram could be. “It’s not enough to post a pretty picture. You have to use hashtags, engage with brands, comment and wade through Instagram to find people who have a similar style and follower base.”

I’m able to see the feed as a cohesive whole, and work with individuals to make sure that their photos match their brand. - Instagram consultant Louisa Wells

Adams says her more polished photos have led to coveted partnerships — she has gotten insider invites to brand launches and hotel openings and has had her outfit photos regrammed by major fashion labels like BCBG.

But while all the Insta-love may have your online persona flying high, experts warn that it can have a negative effect on your real life.

“If you love curating your Instagram image, you should do it,” says Melody Wilding, a Manhattan-based psychotherapist who specializes in millennials. “But I would say putting guardrails on it is helpful. Say, ‘I’m going to spend an hour working on an image,’ but don’t refresh your feed all day looking for new likes.”

Wilding adds that Instagrammers should make sure their identities stand apart from their images.

“Instagram could be gone tomorrow,” she says. “Who would you be if you can’t say you’re so-and-so from Instagram? It’s important to know the answer to that question.”

Expert tips: 8 ways to make you a social media star