I currently work with a school of people who practice prophesying frequently. The topics are broad and plenty, and the methods are few and concentrated. From what I can tell one of the easiest questions to ask God when you want to prophesy over someone is "what do you want to say to this person, Lord?" Sometimes, if you've grown further in trusting your heart with the Lord, you'll already have something about the person on your heart before you even know you are going to prophesy over them. This comes first and foremost with the discernment of the thoughts of the spirit of God. Yet there are certain things that you can ask God, and as you continue to grow in trust of His voice for you, you'll know when He answers questions and when He leaves it up to you to decide. There's an infinite expanse of questions you're able to ask, and I'd definitely recommend things akin to "what do you want to do in this person's life about work? About their business? About their spirit? About their walk with you? To me, the most helpful way that I've found to get to know God's voice is just by expecting an answer when I ask a question. Reflecting on the kind of person I have tended to be over the past while has been a person who mainly talks in questions. If you know me, you'll know that that tends to be the case. There are lots of different types of questions, but there's no real spirit attached to each category, just the questions that the spirit asks. These questions can be asked by any other entity though.
On the other hand, discerning the spirit of a human is a far more other-worldly subject, and the ministry I owe the most revelation and appreciation toward with this is Arthur Burk with Sapphire Leadership Group. They have been into ministering to the Human Spirit far longer than even I've been around, and as such have an expanse of materials with layered approaches to blessing, loving, and unpacking what God has placed in us. Furthermore, he's one of the most biblically grounded preachers I believe I've listened to, without all the systematic theology that often gets attached to those proficient in the Bible. Part of the reason I love the Bible in the first place is because of the sheer amount of mystery that it contains. If you can explain to me why the Israelites ran in 2 Kings 2, I'd probably give you a hug, and maybe even send you a blessing. Then again, if you want a blessing, just ask.
All this to say that there are things that have helped me with discerning the human spirit, and this ministry has been the biggest contributor by far. But I'm working on becoming proficient on my own, and if you do go down this road you'll learn that it's not just some on-ramp and then you're going. It's a very long country road with bends, and winds, curves, and places where you must slow down to avoid the cars coming from the other side. Your discernment grows the more you travel the road, but just as if it were an infinitely long road in an infinitely grand mountain range, you'll never travel the same mile twice. As such, handling the road with the intuition you receive from driving the car is just about the only thing you can count on. That and being able to see ahead much farther in some cases, and being willing to look ahead to other curves in the distant future that will eventually get hidden behind the next curve.
Beloved, I call your spirit forward and bless you with the foreknowledge and intuition to look ahead at the curves that are coming on your road. I bless you with a comfortableness and familiarity in your mode of transportation, and I bless you as you continue to grow in confidence with handling the road with the necessary skill and forward motion to continue your momentum. I bless you with knowing when to take a side road off the main route, and when to continue on the path that you had been on. I bless you, spirit, with the ecstatic joy that you may have in the process of your driving. In the name of Jesus, I bless you. Amen.