Table tennis is less about tips and more about practice.
1. Have you practiced good looping technique?
2. If the answer to (1) is yes, have you practiced using it on a variety of long spinny serves?
If not, it is no surprise that you are struggling to do it and the bottom line is that you have to go to the table and practice doing it. I didn't have serious practice doing it for way too long. And after 3 hours of coaching doing it, I got much better at doing it.
The "tips", if there are any, is that the more topspin on the serve, the shorter the stroke. The faster the serve, the shorter the stroke. The timing for serves is different as the ball trajectory is not the same as a block, push or loop, though some half-log pushes are similar to half-long half long serves. Practice looping the ball with different contact points to adjust for the spin incoming. Avoid dropping your racket below the table to loop sidespin serves.
But tips are tips - the real thing is to practice - you don't learn anything from tips - you learn from practice and the tips inform your experience and help you hone certain things or think about them differently.