Here are some links that help explain how best to use Tube Toolbox.
Getting Started Guide
Bulk Sending Guide
Gather user names using one of our gathering methods (gather from user/page, gather from search results, targeted spider search). Then contact them (share video, send message, etc) and invite them to subscribe to your channel.
Gather from pages/users/search terms that are relevant to your channel. Contacting random users will result in them marking you as spam which gets your channel suspended by YouTube.
Don't run Tube Toolbox 24 hours a day, 7 days a week. We suggest running it no more than 10-12 hours per day and to take a day off every few days. YouTube monitors for activity that doesn't appear to be "human-like".
We also have a feature called Multi-Feature Sending that rotates through all the features and assists by setting the time delays for you. http://www.tubetoolbox.com/Blog/post/Multi-Feature-Sending.aspx