"What books of the Bible do you know well, and which would you like to more fully get under your belt?
What biblical doctrines do you have such a good grasp of you're ready to teach them to a new believer, and which do you need to study more?
What fruit of the Spirit are most apparent in your life, and which do you need to grow in?"
A spiritual assessment is answering questions like these, and it's ideally done with a friend or mentor who can help you take the next step in your spiritual growth. It could be an excellent thing to do as a small group or family. One of the best spiritual assessments I know comes from the book The Leadership Baton. I'll be mentioning it again in my sermon on Sunday. If you choose not to buy the book, you can find its excellent spiritual assessment here.