Jeff, welcome to the forum!
Bottom heat is supposed to help, too. I use a home heating mat on low, with a pyrex tray on top to make it waterproof. It's indoors on a table by a window with filtered light. I've had good success with it so far. It's not big enough for a flat, though.
A very loose medium helps avoid rotting - some even use 100% perlite. I use 100% Turface (kiln-fired porous mineral granules).
Also, increased humidity is helpful to keep the cuttings from wilting. More leaves gives better rooting but also more wilting, thus the need for increased humidity. Frequent (automated) mist sprays are the best, but a loose plastic bag works.
This forum has a lot of discussions on cutting propagation. You can spend hours reading them! Enjoy.