I think an effective tag line should contain SEO keywords
So the tag long would be a combination of keywords specific to your brand (ex: location, specialty, qualities, style, demographics)
This all goes back to branding. On a piece of paper write down words that you think describe your brand
Some keyword ideas....
Descriptive features: Luxury, handcrafted, handmade, elegant, country, minimalist, apothecary style,
location: your state, city, southern, east coast, west cost, midwest
Materials: hemp wick, soy, cotton wicks, coconut, apricot wax,
Strong selling points: long lasting, 100% ______, strong scents, "triple scented" (whatever that means lol), paraffin-free, eco-friendly, custom fragrances, phthalates-free