My advice for dealing with bad employees is to hire slowly and dismiss quickly.
Meaning that in the first big problem, it is better to either dismiss the employee or change his job to something he hates, and with more work and pressure, he will resign.
As for self-development, keep reading on three subjects: business, advertisement, and your field.
Anyone who wants to succeed needs to learn the business and follow channels that talk about business. After that, learning about advertising and the way it works.
The final step is to improve the business. For example, in a clothing shop, learn the way of sewing, the differences between fabrics, and everything in relation to fabrics, fashion designers, their lives, and more.