Use a very sharp lame, razor, or serrated knife
Score the dough just before baking
Keep the blade at a shallow angle, about 30 to 45 degrees
Make confident, quick cuts
Cut about 1/4 to 1/2 inch deep
Score one main slash for a basic loaf
Use multiple cuts for decorative patterns
Dust the dough lightly with flour if needed for visibility
Chill or firm the dough if it is too soft to score cleanly
Avoid pressing down and dragging the blade
Score in a way that directs oven spring where you want it
Work fast so the dough does not deflate
Bake immediately after scoring