i've never grilled kale, but i grill a lot of romaine, iceberg, broccoli, onions, and corn.
for broccoli, i hit it with some evoo and kosher salt. indirect mostly, right on the grates
for lettuces, i cut in half (or wedge for iceberg) evoo, s&p, and freshly grated parm reg.
if i'm feeling adventurous, and it appears that my cheese is well stuck to lettuce, i'll grill over direct - cut side down.
otherwise i go indirect cut side up
for onions, core it out 3/4 of the depth. cut a plus sign or asterisk (*) almost all the way through (same depth as core hole), drop in a beef bouillon cube, pack the hole and cuts with butter. season with s&p, wrap in foil, grill indirect until the whole thing is soft and squishy.