How can I find the area in which God wants me to serve?
This first step may sound like a no-brainer but you'd be surprised how many believers skip it. Be sure you've come to the Lord and expressed your desire to serve. Understand that God wants to bring you into the center of His will and walk in the confidence that He will lead you—even if you don't happen to be seeing the path right away.
To what are you inclined?
Often areas of service are found through our natural (or supernatural) inclination toward a particular area. Do you have a burden for teenagers? How about ministering to seniors? Maybe you love organizing or fixing things. Perhaps God has put a love for music in your heart. The things you are drawn toward may be from the Holy Spirit leading you toward a place of ministry. Bring those things to God in prayer and ask Him to open doors according to His will.
Be available and be willing
Quite honestly there are those who will quickly offer their service, but when the time comes for things to be done they are rarely available. If you really want to serve the Lord it's probably going to involve some kind of sacrifice in terms of your time and energy. Make sure you heart is really willing.
What needs to be done?
Some people fall prey to "analysis paralysis" when it comes to understanding the exact calling God has upon their lives. As a result they never actually do anything because they're constantly waiting for that special something. While you're waiting for specifics on the Lord's calling on your life, just get busy. Look around and see what needs to be done and ask how you can help. One pastor I know came to church and saw how everything on a Sunday was prepared and ready and he knew that there were people working behind the scenes to get it that way. So he asked an usher how he could help. He was told that if he was willing to come 30 minutes before service and stay an hour afterward there were plenty of things for him to do. That's how he started serving.
Stepping Out in Faith
Finding your calling may be a matter of being willing to try various avenues of service just to see what the Lord shows you. Not long after Sue and I started walking with the Lord we were asked to help out in our church's senior high youth group. Frankly I was a little dubious about getting involved, but Sue really wanted to, so we gave it a try. Not long after we started the person leading the group left it in our hands. I was thrust into a teaching position and it was then I discovered the Lord's gifting in my life—teaching the Scriptures.
May the Lord bless you as you seek to serve Him with your whole heart.