I feel like God is calling me to enter the ministry. What do I do now?
Before you do anything, you need to confirm the call that God has placed on your heart. Seek the counsel of a trusted pastor, search the Word of God, and most of all, pray, pray, pray. It is important to realize that sharing the Gospel with others is the highest calling of any believer. God plants within us the desire to find the lost, share the Good News with them, and see them come to a faith in Christ. There is no greater purpose.
While that is the calling for all believers, there are those whom God has set apart to serve in ministry at a deeper level. These people, like yourself, have felt their calling rise up within them and cannot contain it, let alone imagine doing something other than that for which God has intended them.
If this describes you, then the first step is to become prepared. This can only be done through much prayer and Bible study. It is also vital to your growth and maturing process that you are actively and loyally serving in a church body.
Your particular denomination will have guidelines about qualifications for leadership. You can most likely obtain these guidelines from your pastor. You must be willing to do what it takes to meet those qualifications while being a servant in your church.
As a potential leader, you need to constantly check your motives. You can do this by answering some simple questions. Will you sweep the parking lot of your church if no one else will? Will you clean a bathroom if there is no one else around? Will you visit the sick, or help the poor? If you hesitate, then be sure to spend some time praying that Jesus will show you the type of servant leader that He was. Would you wash the dirty, smelly feet of your congregation? That is a leader.
"Thou compassest my path and my lying down, and art acquainted with all my ways" (Psalms 139:3).
"The Lord will perfect that which concerneth me: thy mercy, O Lord, endureth for ever: foresake not the works of thine own hands" (Psalm 138:8).
"I will instruct thee and teach thee in the way which thou shalt go; I will guide thee with mine eye" (Psalms 32:8).