Answer from Dave Kashen, CEO, Worklife, acquired by Cisco.
Like in most situations, you will be more likely to achieve the outcome you want if you are intentional.
Agendas: You need these when there are a group of people who need to know the focus of the meeting in order to gather their thoughts or materials and show up prepared. Agendas also have the hidden benefit of helping you stay on track during the meeting. There's a way in which the agenda starts to feel like a third party arbiter of what's 'in-bounds and out-of-bounds for the meeting. So, if people begin going off on tangents, it's easier to reign the conversation back in.
Depending on the meeting, it can be useful to collaboratively create the agenda by giving others the chance to add topics they want to discuss. Also, setting standing agendas for recurring meetings is a relatively simple, high-leverage way to deliberately create a process for your team that ensures that it has the right conversations that enable it to accomplish the right stuff week in and week out (and, yes, I'm co-founder of worklife.com, which streamlines the process of creating/sharing agendas and running effective meetings).
Goals: Sometimes people write their agendas in the form of goals, but, more often than not, agendas are a list of topics. It can be useful to get even more clear on what you'd like to achieve by asking the question: "What would we like to be different by the end of this meeting?" You can add the goals separately, or frame the agenda as a set of goals (e.g. instead of making “South America launch” as the agenda topic, you can write “Decide whether to launch in South America, and agree on budget for marketing around the launch”).
This way, people know what the intended outcome is for discussing that particular topic. One of the reasons people get so frustrated in meetings is because they think have different understandings of the goals (e.g. one person thinks the South America discussion is to create the strategy and plan for launching and another thinks it's meant to simply decide go/no-go -- and that they'll create the strategy some other time).
Preparation: For more strategic and decision-making meetings, the battle to make sure that the meeting is effective is won or lost before it starts. Preparation can help to specify what pre-work you want people to do or what materials you want them to review before the conversation to make sure that everyone is using their time together most effectively. Executives at Amazon famously spends the first 10 minutes of the meeting reviewing a one (or multi) page document that outlines the problem and key considerations.
Experience: One of the highest-leverage moves that most manager fail to make is getting everyone clear on the experiences you want to create during the meeting. How do you want people to feel during the meeting and when they walk away? Excited, inspired, urgent, empowered? Spending just a minute or so setting the group’s intentions can make a world of difference.
How you show up: One of the critical factors in creating the desired experience for meeting participants is being intentional about how you show up. Do you want to be perceived as confident, relaxed, enthusiastic, courageous, or authentic? Try to spend a minute setting your intentions for who you're going to “be” in the meeting, and you'll notice a world of difference in how people relate to you and what you're able to accomplish.