Like Paul said definitely keep the yoyo level. It’s going to be really hard to land if the yoyo starts to lean to one side.
One thing that may help is that when you pop it up, try to make it pop straight up vertically. A lot of the videos say it needs to hit the top string, but don’t hit it too hard because it will force it down faster than you can cross your hands.
That being said, I wish you luck. It took me 3 months to learn spirit bomb, and that was practicing it almost every day. I’ve heard that some people have a harder time with spirit bomb than others, just like boingy boing. I was definitely one of those people. Every time I pick up my yoyo, I do at least one spirit bomb just because I still don’t land it every time. I love that trick though and it was worth the effort.