The short answer on ‘how’ to prophesy isn’t so much a matter of ‘stepping out in faith’ as it is a matter of learning to listen to the Father. Think about it. Jeremiah, Ezekiel, Elijah, etc., never had to step out in faith or try to prophesy. The Word of the Lord CAME TO THEM.
If they didn’t have to try, no one under the better covenant of grace needs to try, either. Instead, relax, earnestly pray for your brethren, and listen for what the Father may have to say.
Don’t stress if he doesn’t say anything, or show you anything all the time. Remember that your first ministry is worship. The gifts flow more readily from that place.
One thing I used to do, and still do from time to time is I get up before everyone else in the house, and get quiet before God. During that time I either don’t speak at all, or I speak to no one but God. If you try this, be sure to plan ahead with spouses and family members so they don’t think you’ve gone off the deep end.
A lot of times our lives and minds are so cluttered with ‘noise’ that doesn’t even matter, and we are either distracted or just neglect the fine art of listening to UNDERSTAND instead of to respond.
That also helps in our human relationships. Because we focus so much on how we want to respond or what we want to say next, we frequently misunderstand each other. Not surprisingly, we do the same thing with God, so even when we do hear/see something from him, it’s distorted by the noise of life, culture, opinion, and so on.
So, get quiet, and start listening to understand, and see what happens