I get 100% every time...
Like all here, we all think our own special way ... is well, so special...
If you are staying in soil, it is so much easier to clone into soil...
If you are going any other medium, do not start in soil, it's harder to go from soil, to Hydro, as an example...
Plugs to Hydro for sure...
I clone into a 50% Miracle Grow "Seedling" soil mix...
mixed with 25% Perilite...
And 25% Vermiculite...
100%... every time... I never mist LEAVES....
I mist under leaves onto medium...
I have found: misting leaves, only over waters leaves and promotes droop...
The Miracle Grow seedling mix has enough nutes to get your clone through the root stage...
I get roots in 7-14 days, transplant soon after...
Of course, perfect conditions... and light perfect...
CFL's.... Find what works 100% never loose one, perfect... then stick with it...
Are you using a seedling heat mat as well ?