It is a very good way to grow in your faith and understand it better. Before I ever went out witnessing, I thought that I would have to memorize all the different arguments, for everything. After a while, I realized that I would never get out and do it if I kept on "preparing". If you just go out and share your faith, you will see what kind of questions people are going to ask and be able to study those topics.
“Believe on the Lord Jesus Christ, and you will be saved, you and your household.”