Frok,
Where are you located? Finding a local mentor that you can have lunch with once a month is cheaper and far more valuable than a seminar.
What kind of environment do you work in? Managing a remote sales team vs an inhouse group of engineers is a massively different skill set.
Couple of basics:
1. Set clear goals / expectations then stay accountable to them (applies to both you and those you manage).
2. Take big picture objectives (grow the business!) and break into a series of steps. For example, if you are leading sales people who want to make $100,000 a year, you can break that down into how many calls or meetings they need to have per day (even per hour) based on closing rates to achieve.
3. Realize that most everyone has same basic needs. Security, respect, purpose. Create an environment where these are abundant.
4. While needs are the same generally, people are not. Learn the order of importance those needs are for your team. Sales people are risk takers and can thrive in that environment. They can be rewarded with commissions and bonuses and it drives them.
Engineers, scientists, and accountants are generally risk averse and prefer stability over "the promise of tomorrow". Know your people and adapt the environment and management style to them.
5. Don't try to be perfect. You aren't no matter how many courses you take or books you read. People will value honesty and trust infinitely more than technique or tricks learned from a book.
Basic building blocks for sure but kudos to you for wanting to better your abilities. Good luck on your journey!