Enroll in a public speaking course if you're in college. While attending the classes, take notes that you think will be important to know in the future and ask the professor questions if you're confused about certain techniques. If you need more personalized assistance, ask your professor if you can meet with him in his office on certain days to practice your speeches so you'll be prepared when you give them in class.
Attend local workshops that help people improve public speaking skills. While the guest is speaking, write down five questions on which you need more clarity; at the end of the session, ask the guest those questions. If you see small booklets or brochures at the workshop that give pointers on improving your public speaking skills, take some for study purposes.
Practice your speaking skills. If your manager asks you to lead the staff meeting in his absence, prepare for the meeting by going over the information he gives you. While at home, write out a mock script of the meeting you'll have to conduct. Ask your family to play the role of the employees while you lead the meeting. Afterward, ask your family to give you feedback on how you can improve the speech.