The best salespeople, marketers, and businesspeople are those who can walk into a meeting both prepared and ready for anything. Every entrepreneur has to be ready for every kind of meeting, from those that go perfectly from the first moment to those that quickly become testy. Here's how.

1) Be an Expert on the Person You're Meeting

It's elementary to do your homework on whomever you're meeting, but it's time consuming to pull all the information together. Charlie just released its new, free iOS app and Outlook integration. The app sends you a digest on someone you're meeting as long as you put the person's email address into your calendar. The digest includes details on the person's company, its recent news, and its potential competitors. A premium version will shortly offer further insights and updates. Charlie is part of the commonsense idea of knowing everything you can before a meeting, which is surprisingly uncommon. You should know at the very least who the person is, what he or she cares about, and who his or her competitors are before you go in there. There are far too many meets ruined by the failure to prepare.

2) Know Your Product Completely

PR professionals and salespeople consistently fail to understand the product they're pitching, and it's a sure-fire way to lose someone's respect, especially if you want his or her money. Sean Kester, a product manager at sales software company SalesLoft, wrote a piece about being a successful sales development representative that started with a key point: You've got to be an expert. Imagine if a new laptop only included half the specifications on the website? You wouldn't buy it, because you wouldn't know if it was the right machine for you. The same goes for any pitch. You need to be completely aware of why a product is awesome, which involves knowing everything you can about it.

3) Tailor Your Message

If you're about to go on a date with someone, one of the basics is to get to know the person: what he or she loves and hates and wants and needs out of life. The same goes for any business meeting. If you have a product that does a hundred things, you should learn during your meeting even five of them that will change someone's life. For example, ChatWork is a Slack-like chat program with built-in task management and voice-video chat. There are many, many other integrations, but a company that uses Skype, Asana, and Slack could benefit from simply putting their functions in one place. Selling the entire kitchen may not be worth it if someone's sink is broken.

4) Be Human and Real

Though every business meeting needs to be met with some degree of care, you should never be afraid to have an honest conversation. For example, in a job interview, if you see inherent problems in a product you'd be working on, you should mention them in a way that's fair and great. If you're asked how you're doing, maybe don't mention your problems at home, but admit you're tired, or that it's been a long day. Many meetings are endlessly mechanical and boring, and many people appreciate a human, loving approach. This may mean being willing to say, "I read some of your blog posts, and I don't agree on these things." As long as you're nice enough, you can make close contacts by being honest.

5) Follow Up

It's become way too common to see a deal turn to dust after a great meeting, because there was no clear communication after the fact. Even if it's a simple "thanks for a great dinner last night; I would love to talk more," that means a great deal to many people. You don't need to send flowers or a gift basket, but you should always make sure to tell people it was a great meeting--perhaps crack a joke on something you talked about. Manners have been lost, thanks to digital communication, and it may be time to bring them back.