I would say 75% of my business is done through custom orders. I am no expert but I do want to share with you what I have learned through my years of doing them. There are 2 parts to consider in the custom order process. (Yup there are only 2) The customer and the artist. I am writing this more for the customer's side, but artist please read too, it may help save you from further headaches.
The customer actually has more to do than the artist and has more responcablilities. First the customer needs to know what it is they are needing, see if they can find it and if after searching the internet, magazines and stores they can't quite find what they are looking for it's time for them to consider have something made custom.
My suggestion for the customers is to really know what you want, if you are not sure comb through magazines, pick out pictures, colors, patterns, any ideas that you think will help the artist understand what you are looking for.
Now I say this with a warning, please do not pick something out of a magazine and ask the artist to replecate it exactly!!! I will not do that and most artists I know won't either.
Now that you have a better idea of what you want it's time to find an artist that can do the work. Most artists have a style that they work in, it's what makes their art unique. Some artists can do several styles, but keep in mind that you are wanting something custom so finding an artist that can create in the style you are wanting is critical to the success of the piece. There are several places to look: craft fairs, galleries, even online.
Etsy is a great resource if you don't know about it, you can look through 1,000 of different artists and see their work and convo/email them right on the site.
When you approach an artist about doing custom work don't be upset if they say no, some just don't like doing them. You can ask if they know someone who might. If they say they do custom orders, explain what it is you are looking for
in detail and see if they are interested in working with you. If you clipped out your ideas, email them to the artist or see if you can meet face to face and go over the details. Let them know size, quanitity, style, timeline (if you have one) any details you know already. Don't be afraid to ask questions! Especially if you have never had a custom work of art done before.
Look to the artist to start filling in some details of their own: their timeline for drafts and delivery, what to expect from them, how to get a hold of them. Ask how they work, if you will be able to see progression in the piece as they work on it. Ask to see samples if they have something they have done similar. Get a quote from the artist on cost and how they would like to do payments. Most artists want up to 50% up front to cover costs of materials, in case you back out at some point in the process. You can ask to push back the first payment until after you see the first sketches, so that you can see if you like what they come up with. If you don't that is the time to walk away from the deal, but you will still have to pay for their time of drawing up the designs for you. If you talk about this ahead of time, you will know what you owe instead of having sticker shock later.
Expect the artist to put their own spin on the custom order, if you did your homework you will love the artist's work beforehand and therefore love the ideas they bring to the table. Ask for drafts before they start working on the final piece so you can see how they invision your vision.
If you do your homework right you will end up with a custom piece of art that you will truely love without the headaches of misunderstandings. Good luck.
