Right from your Project view, you can add custom links to keep things all organized in one place. Just click the "+" symbol next to your project's Documents & Links section.

Click "Add Link" to view the modal and add your link details such as a custom label and descriptive text.

If you choose to send a notification, your the default contact for your client will be sent your new link in an email.
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If you have the client portal enabled, it will also show a link to your project page for them to view, but if you do not have the client portal enabled then it will just send them a notification without any reference to the client portal at all.

Once you've added your link, both you and your client can use it, making it easier to keep everything organized together.