Create your contact list. Save the employers’ contact details you have gathered, especially the ones you are interested in the most.
Connect on LinkedIn with the employers you did not have a chance to meet during the fair, if possible. If one of them has an opportunity that really interest you, you can send them a message on LinkedIn explaining why you are interested in the opportunity.
Research on the opportunities you learned about and see which ones you would consider applying for.
Update you CV and cover letter so that it relates more to the opportunities or jobs you are applying for.
Send a thank you email to employers you have met and talked to during the fair.