To create dimensional lines, hold bottle like a pencil and gently hold tip to the surface. Always hold the applicator tip against the fabric, squeeze and drag tip along fabric surface so that paint seeps into fibers. This is what bonds the paint to the fabric.
For raised line work, hold bottle at an angle, allowing more paint to escape. For flat line work, hold bottle straight up and down, allowing less paint to escape.
To make a comma shape, hold bottle straight up and down and squeeze out a dot of color, pulling it toward you and quickly releasing pressure. Paint will naturally form a graduated tip.
A comma can quickly turn into a heart by adding a second comma as a mirror image with tips touching.
Dimensional designs need "flex points" on fabric for durability and movement. Do not make long continuous lines. Instead, make a 3-4" line, pick up the tip and start again by placing the tip just past the end of your first line. Repeat until you've created the desired length.