Generally speaking... for lighter shades, use less drops. For darker/vibrant shades, use more. Typical usage is between 1 and 10 drops per pound of wax.
Also, keep in mind these factors that may affect the amount of dye required for
the desired shade include:
• The opacity of the wax
• Wax additives such as stearic acid, polymers and
microcrystalline wax
• Fragrance
Be sure to test usage amounts in your own products to obtain the colors you want while not impacting the performance of the wick/candle. In some cases, too much dye can impact fragrance throw and/or introduce wicking issues.