The problem with shortcuts is they are usually not repeatable or scalable. For example, a viral video or website can provide a boost of growth, but you can't predict if the next thing you produce will also go viral.
What you want to find is a predictable way to generate sales where the economics work. The economics work if the cost to generate a sale is 1/3 or less of the lifetime value of the customer. Even if it takes a lot of effort to generate the sale, if you have a predictable way to generate leads, and you know how many leads you need in order to produce a sale, and you make a good profit on that sale, you are golden. You can then ramp up your lead gen and you know your sales with grow faster. It doesn't take any luck to display more ads, send more emails or hire sales reps.
This is the strategy we used to grow from $0 to $1M in ARR in six months. We could then go to a VC and tell them that if they invested $X, we could turn that into $Y in ARR. It made fundraising pretty simple for us.
tl;dr Treat sales and marketing like a science and design a repeatable process.
Test on a per-channel basis, ie. marketing spend per customer acquisition, immediate customer value, (conservative) value over customer lifetime. Frankly anything but the initial sale is largely bullshit, but investors love it if you can show nice numbers here. At my first startup (China-wide multilingual hotel reservation platform) I had an angel work through this with me and come to the same conclusion I did: we'd tried pretty much everything, so customer acquisition was either going to be very slow organic or expensive and cashflow negative / capital intensive, save some kind of channel partnership deal.
Direct sales and paid ads are both solid channels. Others that I've seen work are SEO, Content Marketing, Social Media Marketing, Partnerships, API Integrations, Meetups, Conferences, Engineering as Marketing, Viral Design, Affiliates, PR, Newsjacking, Branson-style Stunts, User Incentives (like Paypal giving people $20 for signing up), etc...
What works depends a lot on what your price points are, what your competition is doing and your stage of growth. The worst thing is when a startup's ideal channel—and it usually is just one or maybe two channels that will work really well—happens to be one that the founders dismiss without even realizing it. In fact, a lot of technical founders would dismiss the exact kind of direct sales that worked so well for you.
for software engineer's approaching marketing for the first time.
That was a mistake that we made. We started by hiring smart people and trying to let them figure out how to sell. I strongly recommend NOT doing that. In startupland, time is your greatest enemy and you don't have time for people to learn. Also, you probably aren't a sales expert, so you can't teach them what they need to know to be great.
Another mistake we made was hiring people who were good at selling other things. Medical device sales, consumer product sales, SaaS sales to SMB, SaaS sales to enterprise, etc. Once again, great sales people in other types of sales can learn to sell into your market, but it can take a long time and you probably don't have the expertise to teach them.
We spent 12 months trying to use smart people with no experience and sales people that were great at selling into different markets and generated essentially $0 in sales. We were ready to give up. Finally we hired a senior sales person from a competitor that was selling a very similar product, into the same market (med-large business) and we've taken off since then.
Your growth hack/shortcut was in the end, to poach a sales guy from a competitor who had clout with a bunch of customers in your field.
I thought sales was just sales and if you could sell one thing, you could sell anything. What I didn't realize is that selling B2B to a small business and selling B2B to an enterprise is as different as a skill set as writing compilers and building web scale applications. It takes years to get really good at each one of those things.
I've also learned that as a founder/CEO, most of my time is spent selling. I was a software engineer for 10 years and now I pretty much spend all day every day selling. Selling investors on why they should buy 25% of my company, selling potential hires on why we are the next big thing, selling the board on our new plan, selling customers on our product and selling employees on the company vision.
Once we had someone who knew how to sell SaaS to medium and large businesses, we just started doing what they considered obvious and fundamental. It was a revelation to us. :)
We started using software to send emails, track opens and clicks and then call prospects that did any of those things. You have to do a lot of dials, but eventually, someone answers. Of course they're not interested, so back to dialing. After 30 answers you'll get one that is interested.
Sales is just a numbers game. It's hard work. It's hella hard work. But send enough emails and make enough calls and you'll make some sales. And there is nothing like the feeling of closing a sale after grinding it out. Over time the sales add up, and before you know it, you are having a party with silly string and noise makers because you passed $1M in sales! (That was a fun day!!!)