“I’ve seen startups spend thousands of dollars inefficiently as a result of not having optimal signal in their paid acquisition campaigns. I’ve also spent millions at companies such as Postmates refining our signal to the best possible state,” says growth marketer Jonathan Martinez in a guest column for Extra Crunch this week. “I’d like every startup to avoid the painful mistake of not having this set up correctly, instead making the most of every important ad dollar.”

The TechCrunch team has been busy this past week, especially with Disrupt next week and the iOS 15 release date quickly approaching. If you haven’t already registered for Disrupt, it’s not too late to get a ticket. We’re excited for all of the sessions, including “The Subtle Challenges of Assessing Product-Market Fit” on Tuesday, September 21 from 2:05 PM – 2:45 PM EDT the Extra Crunch stage. The marketing world was full steam ahead this past week, Martinez covered how to optimize signal and Miranda Halpern spoke with Vivek Sharma, CEO of Movable Ink about the impact that iOS 15 will have on email marketers. We also had guest posts from Bryan Dsouza of Grammarly and Xiaoyun TU of Brightpearl. More details below.

If you didn’t already hear, we’re giving away one free ticket to Disrupt, through the Experts survey. Check out the schedule for Disrupt, and read on to learn about the giveaway details:

• Have you already submitted a recommendation? That’s great — we’re counting all previous survey submissions as an entry for the Disrupt ticket.
• We’ll also enter the next 100 survey submissions into the giveaway.
• Do you want to submit 10 recommendations to increase your chance at winning? We love the enthusiasm, but we ask that you only submit one recommendation for each marketer that you’ve worked with.
• Don’t know what to say in your recommendation? Start with what traits they had, what they did to help your company, how their work affected your business and go from there!
• We manually go through all entries, so please don’t copy and paste the same response multiple times.
• Have a question about the giveaway? Send us an email at ec_editors@techcrunch.com.
• The survey will stay open, but we won’t be counting submissions as entries to this giveaway after Sunday, September 19, 11:59 pm PT.

Marketer: Andrew Race, Juice
Recommended by: Orin Singh, Merchant Industry
Testimonial: “We were referred to Juice by a family friend of my company’s owner and as a personal courtesy they said they were giving us their best guy. Naturally we thought that is what everyone says but they were not kidding. Andrew was singularly leagues above our previous marketing company. Having someone so knowledgeable and willing to learn a new industry proved to be the turning point for us.”

In growth marketing, signal determines success: Martinez learned from his mistakes, and share the lessons learned with us. From selecting the signal, to how to enhance it, Martinez covers key aspects including how to take advantage of iOS 14. He says, “So how do you stay ahead and continue moving the needle on your growth marketing campaigns? First and foremost, constantly question the events you’re optimizing for. And second, leave no stone unturned.”

Marketers should plan for more DIY metrics as iOS 15 nears: The release of iOS 15 will change that playing field for marketers. They’ll have to rely on metrics that use zero and first-party data rather than relying on email open rates as the main metric. Miranda spoke with Sharma about how this release will impact the industry and what marketers should focus on. One tip from Sharma is, “Focus on down funnel metrics like clicks and conversions — that’s what it really comes down to and that’s the truest indicator of engagement.”

(Extra Crunch) Demand Curve: How to get social proof that grows your startup: Nick Costelloe, head of content at Demand Curve, dives into social proof and how startups can use it to their advantage. On social proof, Costelloe says, “Have you ever stopped to check out a restaurant because it had a large lineup out front? That wasn’t by chance. It’s common for restaurants to limit the size of their reception area. This forces people to wait outside, and the line signals to people walking past that the restaurant is so good it’s worth waiting for.”

(Extra Crunch) 5 things you need to win your first customer: Dsouza, product marketing lead at Grammarly, walks us through how to win your first customer. He includes explanations, how-tos, and practice use cases. Dsouza says,” . . .ask any founder what really proves their startup has taken off, and they will almost instantly say it’s when they win their first customer.”

(Extra Crunch) 4 ways to leverage ROAS to triple lead generation: TU, global director of demand generation at Brightpearl, walks us through ways to use return on advertising spending (ROAS). She says, “When you choose a return metric, you need to make sure it matches your company goal without taking ages to get the data.”

Tell us who your favorite startup growth marketing expert to work with is by filling out our survey.