"Ask for critical feedback!"
Such an easy advice to give.
And such a hard advice to execute.
In real-life getting proper constructive feedback is tough.
Here are the 2 principles I use when I ask for it.
1. The person I am asking feedback from has to feel safe.
It's my job to make them feel that they won't hurt my ego.
For example instead of telling them "I need your feedback", I tell them:
"I need your critical and honest feedback. The more honest it is, the more you'll actually help me"
2. The feedback has to be focused.
Asking "what do you think about my product landing page" is useless.
But asking "Do you understand what are the benefits of my product?" or "Can you understand what my product does?" or "would you feel safe to buy my product?" is much better.