Have You Considered Writing Greeting Cards?
First, note that this is not easy. Just like writing for children is not easy simply because it takes fewer words, likewise greeting cards are not easier to write because they have fewer words. Unless you are a gifted writer that doesn't need to hone your writing skills, writing for a greeting card company can be challenging.
Writing must be tight when writing greeting cards. Every single word must be just the right word. Authors of this type of work must learn to write each and every card as if it were to one special person while at the same time making that card appeal to a mass market.
Research your markets and write to a specific target audience. These are important skills to learn. What you may put on a card for an adult may be totally inappropriate for a child even if both are for a birthday. One company may accept funny verses and another may only take serious prose. Research before you write and it will save you time but it will also help you to learn to write for a specific target audience.
Writers must also follow the writer's guidelines for each publisher they have researched. Guidelines are specific for word count, subject, and voice just like any book or magazine publisher. If you don't follow the guidelines for a particular company it is likely that your work won't be accepted.
Guidelines will not only spell out voice, subject matter, and word count, the publisher will ask for a specific format for each verse. Some will accept several on a typed page while others will want one verse to one 3 x 5 card. Some guidelines will specify if you can send 1, 5, or 10 sample verses and some may want 20. Read and follow the guidelines to the tee if you want your work reviewed.
Additional education may help to improve your chances of being accepted by a greeting card publisher. Search the Internet for courses on writing greeting cards. Sandra Miller- Louden is a well known writer of greeting cards and has an online presence offering free and tuition courses on the subject. Her first book, Write Well & Sell: Greeting Cards was first published in 1998 but more recent editions are available.
Google the topic and a number of books and resources are available from your home but don't overlook the library and your local book store for other resources that may be available.
With persistence and practice, you can write and publish greeting card verse. It may be just the niche you are looking for as a new or seasoned writer.