Design trick I stole and will not be giving back: Pick one accent colour. Use it exactly three times per screen. Everything else stays grey. Same layout, before and after.
The compounding is invisible for the first 90 days. That's exactly why most people quit at day 30.
I'm telling you the number now so I can't quit quietly.
Validation is not asking your friends.
Your friends will lie to protect your feelings. Strangers won't click, and that's the only honest data you'll get.