offer articles which are helpful to your colleagues and your clients.
create a company page if you are more than 1 agent or have a team.
go ahead and use the paid to advertising, especially if you are recruiting other agents.
greet friends who ask to connect with you via a private message.
email on occasion your connections on linkedin.
put your linkedin url on your email signature so people know they can connect with you there.
advertise your linkedin profile occasionally on facebook.
have fun and connect!!