Within your Outreach tab, you'll see some contacts that are ready for outreach and some where outreach is already in progress. You can use BuzzStream's filters to show only contacts that are ready for outreach.
Start by clicking the 'Filter' icon:
This will open your list of Filters on the left-hand side of BuzzStream. To show only the prospects that are ready for outreach, select the 'Relationship Stage' filter and select the 'Not Started' and 'Field is Empty' options.
You may also want to filter out contacts that have been reached out to recently in another project. To do this, select the Outreach filter and filter the contacts to only show contacts that have not been emailed within the timeframe you care about: