What am I supposed to do with my life? Who should I marry? What should I study? Where should I go to school? What job should I try to get? All of these questions are important to followers of God. And good followers of Christ desperately want to ensure that they make the right decisions when they face these, and other, decisions.
I recently read two books on the topics of God's will and/or spiritual discernment. Kevin DeYoung wrote an entertaining little book called, Just Do Something. Tim Challies wrote a less entertaining, less "little" book called The Discipline of Spiritual Discernment. Both books are well founded on Scripture. Both might prove helpful to people who are searching for God's plan.
Perhaps the most important take-away from both of these books is that God's will for a person's life is already contained in Scripture. Of course there is no chapter and verse that tells you what job to take. Instead, God's will that is revealed in Scripture is His moral will for your life. God is very clear that His will for believers involves things like sanctification (1 Thess. 4:3). God's will for each Christian is the same in the sense that He calls us all to make decisions that are based on the teaching of Scripture. God's will for you is based on what is right and wrong. And He has clearly revealed that He desires you to choose to do right rather than to choose to sin.
While God's will is already revealed, this does not mean that choices about who to marry and where to go to school are unimportant. It does mean that we have freedom to make those choices based upon how those choices will help us to be more like Christ. One school might help you know God better. But there might be several schools that are all equal in how they will help you fulfil God's plan. In those cases, a Christian has freedom to "just do something." So, don't be paralyzed about a decision. Don't spend hours and days agonizing between which of two perfectly good options is actually God's will for your life. Instead, limit your decisions to things that will most help you be like Christ. Then make a decision and be content that God's will has been accomplished.