Ask any Silicon Valley commuter and they’ll tell you traffic on the 101, the highway that connects Silicon Valley to San Francisco, is the bane of their existence. Advertisers on the other hand? They live for it.

Landing a billboard along the 101 has become a rite of passage within the tech industry. Last year, Lyft’s hot pink van-on-a-stick and Twilio’s bright red “Ask Your Developer” billboards joined the ranks of Apple and Facebook as iconic 101 ads. These ads are more than just eye candy, 101 commuters are a highly lucrative audience: They’re relatively wealthy, work largely in tech, plus, bumper-to-bumper traffic makes for a captive audience.

As New York emerges as a technology epicenter, the city’s subway has earned a similar reputation. From Oscar to StreetEasy, Casper to Makespace, it seems every New York startup is hopping on the ad train. NYC’s billboards are hot property as well: From Glossier to Outdoor Voices, a short stroll through SoHo paints a tech scene on the rise.

To help startups understand the opportunity out-of-home (OOH)advertising presents for their brand, John Laramie, founder and CEO of ADstruc Project X, the technology company at the forefront of the OOH industry, joined us in hosting a working session with leaders from NYC’s top startups.

Here’s how to approach out of home marketing, as demonstrated by three iconic NYC ad campaigns:

Glossier: Have A Multi-Platform Advertising Strategy

A common mistake founders make is approaching digital and physical marketing with entirely separate strategies, but the most successful marketing campaigns leverage cross-platform synergy. “Glossier understands at its core what they’re doing in other media formats like social and how out-of-home advertising can support that,” Laramie says.

Consider your offline campaign within the context of existing digital campaigns. How can offline campaign inspire digital responses? How does this offline campaign complement existing digital campaigns?

Glossier’s empowering offline copy, for example, has gone viral on social media: “It’s rare that I’m inspired to take a photo of a billboard and post it on Instagram,” Claire Knebl, Senior Manager of Brand and Campaign Strategy at Glossier says. Glossier looks to social to monitor the impact and ROI of its OOH campaigns. “We try to make campaigns people will want to share, from the creative down to the placement itself.”

Another lesson to glean from Glossier: Buses are an under-appreciated ad platform. “Buses are literally massive moving billboards that drive around neighborhoods and you get to select the route,” Laramie says. Plus, they’re cheaper.

MakeSpace: Be Bold

As OOH advertising gains popularity, campaigns are competing not just for real estate but for attention. The bolder the campaign, the more it stands out.

Makespace, for example, white-ed out entire subway cars with no explanation but a simple “MakeSpace Was Here.”

“It was unusual and inspired curiosity,” MakeSpace Creative Director Rion Harmon says, “it’s campaigns that do things a little differently that are remembered.”

OOH is notoriously tricky for attribution. Harmon surveys MakeSpace users at time of purchase. If X% of new users say they learn about MakeSpace from the subway, then that number can be extrapolated based on your total number of conversions to get an idea of how effective the campaign was from an ROI perspective. Promo codes, hashtags, and unique phone numbers are other creative hacks, too.

Another tip Harmon offered the group: Have one campaign on deck to take advantage of remnant media deals.

Oscar: Go Big Or Go Home

Photo credit: Jill Lin, Campaign Creative Director and Illustrator

When “experimenting” with out-of-home advertising, startups are often too conservative in their approach and are disappointed with the results. Oscar, on the other hand, has become known among advertisers for scale of their campaigns. At one point, Laramie highlights, Oscar ran on nearly every taxi-top in all of Manhattan.

Of course, by virtue of being later stage, Oscar benefits from a larger budget than the other companies we’ve talked about, but the sentiment remains: Impact is a function of scale.

“The first qualifying filter when deciding if out-of-home marketing makes sense for your company is understanding spend as it relates to impact,” Laramie says. The average cost for a NYC subway brand train (half car, 570+ cars) averages a hefty $250K per month.

This price-tag is complicated by the fact that startups often demand a clear ROI in order to justify spend - that ROI being an instrumental mechanism to helping raise the next round of capital.

Be sure to adjust your ROI expectations according to your sales cycle. While consumer brands like Glossier may see an immediate impact, companies with longer sales cycles like MakeSpace and Oscar often feel the impact months down the line.