My response comes from multiple perspectives:
(a) working with founders,
(b) working as a founder, and
(c) working as an employee in a few startups
It's too difficult to separate out my experiences, they've all shaped how I view the world today.
(1) Most important mental shift?
I wish there was just one – but knowing that there are so many pieces to the puzzle and acknowledging what you can/can't change is quite a shift.
It's so easy to get bogged down in thinking that we're completely in control and the work we produce can happen in isolation. E.g. this is my code I'm writing and my product I'm building, therefore it'll go how I want it to.
In reality there are a ton of variables – many of which we can't control.
You're laying a few pieces of a 10,000 piece jigsaw puzzle. It requires other people (customers, suppliers, colleagues) to give you the pieces and advise what the puzzle should look like.
(2) Top 2 to 3 growth hacks working today? What never works but founders always try?
Good old growth hacks – we love to think that there's some quick trick that will suddenly get us 1000 extra users. That we'll wake up tomorrow and the Stripe notifications will have been pinging continuously all night.
Sadly the truth is so far from it.
Yes, you may happen to do a Product Hunt launch, it goes well and you get a bunch of users... but what next?
Or you had a tweet go viral and signed up a bunch of users.
The chances are – if it's that great of a hack, it won't be long before everyone jumps on it and its effectiveness plummets.
By all means do these things... but don't rely on them. Think longer term. How can you sustainably get clients and users?
My alternative question is: If you knew that this was going to take 1-3 years to work on, what would you do that could get results sustainably for that period of time?
(3) #1 productivity hack for founders?
Get clear on what you're doing.
It's so much easier to 'do', when you know what you need to do.
It's easy to procrastinate in a sea of options (heck, I've done it before and I'm sure I'll do it again).
But when you've laid out your options, assessed pros/cons and why you might head in one direction or another, it's much easier to draw up a plan you can execute on.