I’m trying to learn the hook before I get to Brent Stole and for some reason I always land in a trapeze. I don’t know how to get that full loop to encircle my finger!
Heavier strings will help that loop go around.
With light or otherwise flowy strings I can do neither Brent Stole nor Hook.
When i learned the hook it really helped to look at it in slowmo.
(ignore the fact that it is a double)
A quick tip:
Think about the trick as doing a laceration but instead of catching the yoyo you let the “loop” go around your fingers and you hook (catch) it around your fingers.
It is a bit difficult but as soon as you get it, you get it.
- Casper
When whipping the string, try pushing your NTH index downward. Like you are wagging your finger at someone who has disappointed you. This will help the loop of slack whip around your finger and into the yoyo’s gap.
I try to visualize the strings ‘U’ shaped loop swinging up into my finger about its width and the outside of the that ‘U’ shape at the yoyo gap. Make sure the yoyo is just below your index finger on the pop up too. That helped me anyway. 
Sho nuff for me too. Dragon string is probably the fastest string I’ve tried other than my own. I have to play it slow on purpose compared to other string or it whips by before I see it. 
for me since I literally just learn Brent stole it what I found it helps to have a lighter Yoyo so the string will whip the Yoyo faster. I also find you want to aim your finger to hit the back string in Brent stole. Hope that helps. And truly you want to learn Brent stole first.
I got a word of advice from someone to keep my NTH still and let the string do it’s thing. It helped me a LOT! I initially kept my feet together and nth finger out keeping still instead of my whipping hand and it all came together! 
Whip it toward your shoulder, or the yoyo will land in a Double Trapeze. But mainly just whip it hard, keep your string tension right, and don’t move your NTH.
Good Luck!