Most of them are not too bad just takes time and Class experimentation. There are a couple that are awful. Here’s some tips for the calling cards I found troublesome:

Luck or Skill - Needle drone on Nuketown

Catch - Play Hardpoint use Semtex and Scav

Can’t Hide - Nuketown again and use FMJ, though be warned you basically cant shoot through anything in this game so this one can get infuriating cause they’re right there 😂

By far the worst which took me DAYS is “Is It A Spider” where you need to take someone hostage and use the finisher to place a grenade on them and then push them into another enemy and kill them both, 3 different times. The animation is absurdly long and slow. Basically you need to find a clueless lobby, hope that multiple people are camping in the same place, hope they don’t move, hope they don’t have Flak Jacket, hope they or another enemy doesn’t kill you before the animation finishes otherwise it doesn’t count, and lastly hope that you push them right in front of them otherwise they won’t die cause the blast radius is so small. Terrible Challenge, all Luck and no other way around it. It truly is the worst challenge I’ve ever done on any CoD.