Having an inventory of your art, and a mailing list, is critical to your success.
A well-planned art inventory will allow you to search and sort your information. It will help you keep track of your work including an image of the piece, the cost to create it, sales/location info, copyright info, exhibition history, and installation info. It will also help you to document provenance (which is the history of ownership and location of your work) which comes in handy for any copyright or other legal issues. It will be invaluable at tax time.
A good mailing list will allow you to search and sort your names and address information, set up categories (friends, family, collectors), pull out information for specific geographic areas, print mailing labels, pull email addresses for email newsletters and invitations, and keep notes about your contacts.
There are software programs you can buy to manage your art business. Cost for the software and features vary widely. My own experience has been confirmed by what I hear from artists: most of the software for artists falls short of being easy-to-learn and having comprehensive features. (If you are using software for artists, I'd love to hear from you about what you use and why you like it, and why you don't.)
It's worth figuring out if a particular software will work for you. If what you use is overly complicated to learn and won't allow you to easily update your information, you'll be less likely to update it regularly.
I've set up a lot of artist inventories and mailing lists, and taught artists how to use them, and my recommendation to you would be to start with a basic spreadsheet. If you later find specialty software that's appropriate for you, it should allow you to easily import or export your existing inventory spreadsheet and mailing list.
Most artists have Microsoft's Excel, or Apple's Numbers, or another basic spreadsheet program. That's all you need to get started and it will grow with you.
If you're a DIY person, here's a tip: For your art inventory, go the the Copyright office website and get copyright form VA (for Visual Art). Use that info for your column headings. Add any other info as column headings that you want to keep track of. It's a good start.
If you want some help with this, I've found that the most cost-effective way is for me to set up your spreadsheet or artist software then to help you learn how to use it. Some artists have me handle it all for them, and that's fine too. I can custom-design a solution to fit your budget and time. Just email me to inquire.
As always,

P.S. If you're like me and love to have great resources around, I suggest you get on the email list for Aletta de Wal's new book "My Real Job Is Being An Artist: What You Should Know Before You Quit Your Day Job (Or Get One)." It'll be published later this year. I've read it, it's fabulous, and will be ordering 10 copies for family and friends. Honest. It's not just one size fits all "how to" or cheerleaderish "self help." It will help you get really clear about where you are and what YOUR most effective next steps are. Email me to get on the notification list, and get special goodies too!
Want to know exactly how we can help you set up your ongoing learning and get it all done? If you haven't already had one, you can request a free 15-minute conversation here. It's a great start!
