Be quiet. In order to hear the Lord's voice calling, take time to pray and meditate in silence about your vocation, especially in front of the Blessed Sacrament.
Find a spiritual director with whom you can be open. Look for someone who can help you to develop your relationship with God and to help you know yourself better.
Ask a priest, brother, or sister in your parish to put you in touch with the vocation director.
Read up on religious and priestly life. Look at good periodicals on vocations and check out the ads.
Write to the communities that interest you.
Visit the ones you feel called to.
Build a relationship with the one with which you have a sense of coming home. Get involved in its summer and monthly programs. Don't just talk the talk - walk the walk with them as well.
Wait for the Lord; discerning your vocation is a process. God's timing is always perfect, but it seldom seems soon enough.