TLDR;
If there was one topic that you'd like a seasoned product designer to deep-dive you with, what would that be? (e.g. interviewing users, usability testing, creating beautiful UIs, landing pages etc.)

Details:
I'm a seasoned product designer having worked in some of worlds largest SAAS companies - working right from ideation, designing, prototyping and testing of ideas. Have a lot of experience in B2B Saas and consumer products - designing, workshopping, interviewing users, usability testing etc.

Having worked with several entrepreneurs previously to provide design guidance, I'm now planning to create a FREE youtube series for entrepreneurs and solopreneurs, who probably don't have enough resources to hire a designer but need help in creating products that solve a problem and also figuring out their design process.

Reflecting on your journey in designing and developing products, which parts of the process did you struggle the most? Which topics would you like me to cover?