To become an expert at cellophane cone rolling for henna, follow these steps:

1. Gather the Necessary Materials: Collect all the materials you will need, including cellophane sheets (pre-cut or a roll), scissors, a ruler or measuring tape, adhesive tape or glue, and a flat surface to work on.

2. Prepare the Cellophane Sheets: If you have a roll of cellophane, cut it into individual square or rectangular sheets. The size of the sheets will depend on the desired size of your henna cones. A common size is around 10×10 inches (25×25 cm).

3. Roll the Cellophane: Take one cellophane sheet and position it in front of you with one corner pointing down. Starting from the pointed corner, tightly roll the cellophane diagonally towards the opposite corner. Ensure the roll is tight and smooth.

4. Secure the Cone Shape: Once you have reached the end of the diagonal roll, pinch the open end of the cellophane together to form a cone shape. Adjust the tightness and size of the cone according to your preference. Hold the cone firmly to keep its shape.

5. Secure the Cone Tip: To prevent the cellophane cone from unrolling, secure the tip by folding it inward or by using adhesive tape or glue. You can fold the tip multiple times to create a small, sturdy opening for henna application.

6. Trim the Excess Cellophane: If there is excess cellophane extending beyond the tip of the cone, carefully trim it with scissors. Trim it at an angle to create a neat and clean opening for henna application.

7. Repeat the Process: Repeat the rolling, securing, and trimming steps for each cellophane sheet, creating multiple cones as needed. Practice rolling cones consistently to achieve uniform shapes and sizes.

8. Test and Adjust: Test your cellophane cones by filling them with a small amount of henna paste and practicing henna application. Assess the flow and control of the henna from the cones. Make any necessary adjustments to the size of the cone tip or the tightness of the roll based on your experience and preference.

9. Practice and Refine: Becoming an expert at cellophane cone rolling requires practice and refinement. Continuously roll cones, experiment with different sizes and techniques, and evaluate the quality and usability of your cones. With time and experience, you will develop the skills to create well-formed and functional cellophane cones.

Remember to handle cellophane with care to avoid tearing or damaging it. Practice patience and precision to create consistent and reliable cones for henna application.