Okay, I’ve tried so many times to get a basic trapeze slack but just can’t land it. >:( Each time i throw the string over my non-throwhand, it either: misses the gap, the wrong string hits the gap, or i drop the yoyo too late and miss the string. Its mostly just not hitting the gap though.
I was hoping if someone could give me some suggestions on how to land this. I’m open to anything. Thanks in advance! 
I assume you’re referring to this trick: YoYoExpert.com - Advanced - Slack Trapeze
When making the motion with your throwhand, try to make it as straight as possible. Tossing the slack over at an angle will make the string go askew.
Take your time when tossing the slack. It makes it more accurate and looks cooler.
Hold the string between your throwhand thumb and pointer when tossing the slack. This can help you guide the string.
Just practice! Repetition and muscle memory is key.
I hope some of this helps!
To me, it helps not to aim the string directly into the gap, but to throw it towards a sorta 8 o’clock angle. Throw it behind the yoyo, not straight on. Not sure if it will help you, but it helped me.
Also, you might wanna try to pinch the string differently, like pinching it while it is at an angle etc.
