I dont think you can learn to use toe clips on a fixie.
Learn to ride toe clips on "normal" bike.
Learn to ride a fixie, slowly on plain platforms at first, then add your clips.
I find that leather straps hold their shape better than nylon and metal clips can be bent up for more space.
Note that clips come in several sizes so use the right one.
Shoe traction needs to be in the Goldilocks zone, not too grippy, not to slick.