There is no one definitive answer to this question - it depends on your specific needs and preferences. However, here are a few options that you might consider:
You could create a new Gmail account for each new project or individual that you need to communicate with. This would give you a separate inbox for each person/project, making it easier to keep track of your correspondence.
You could use a Gmail alias. An alias is essentially a second email address that is automatically forwarded to your main inbox. This means that you can give out a different email address for each person/project, without having to check multiple inboxes.
You could use a Gmail account with multiple filters. This would allow you to create separate inboxes for each person/project, by filtering your incoming messages based on certain criteria (e.g. sender, subject, etc).
You could use a Google Apps account. This would give you all the benefits of a Gmail account, but with your own custom domain name (e.g. email@example.com). This is a great option if you need to give out a professional-looking email address.
Whichever option you choose, be sure to use a strong password for each