At 24, the top salesperson at my company, I was promoted to sales manager.
My first hire was worse than bad -- he actually turned in phony orders...
Next one wasn't much better: the girlfriend of a State Congressmen. I figured she'd have "connections" We'll never know. She barely made sales calls.
I learned a few things. Trial and error. I got better at hiring. Not great, but better.
Then I had an idea to help radio stations sell to previously unsold advertisers. Started my own company. Within 2 years, Radio Profits Corporation had nearly 200 salespeople across the US, UK and Germany.
But our sales hiring failures were killing us, blocking profitability. Turnover was 50%+. The 80/20 rule was in full force: 20% of our sales team were studs, 80% were duds.