"Paint the lily" means to unnecessarily embellish or add enhancements to something that's already beautiful. There are several synonyms for this phrase, including "gild the lily," "over-embellish," "over-decorate," "over-adorn," "overdress" and "over-ornament." Each of these phrases suggests adding excessive, unnecessary decorations or enhancements. While it's important to add the right level of embellishment to something, going overboard can make it look garish or unrefined. It's important to find the right balance between adding the right level of enhancements without going overboard.