Becoming a better trainer takes practice. Advice from those that have already made the mistakes is immensely helpful. Find a mentor that you can trust. Form a partnership in learning with someone whose opinions you value, perhaps an author, a corporate trainer, a colleague, a teacher, or some other talented member of your community. Have lunch. Ask questions. Take notes. Put the tips you learn into practice. Make mistakes. Ask more questions. Shadow them or co-facilitate a session with them. When you are finished, ask for feedback on your efforts. Accept constructive criticism and implement suggestions given.
Another idea along this same line is to meet with a group of professionals in your field. Once a month get together and discuss your three favorite tips or activities. Bring your best and share them. In half a year, your group will have dozens of best practices from each other.