I've always struggled a bit with doing commission work, but still greatly appreciate the fact that it is possible for me to supplement my income through making art.
I much more enjoy making art for myself as a means of venting and learning new techniques, and usually have a hard time not feeling too pressured by commissions.
Over the years I have developed some commission practices that help keep things fair to both me and my commissioners. I think these work very well for part time/supplemental income. To support yourself full time, you may not be able to do all of these.
1. Open for things you enjoy and do well - don't be afraid to limit your commissions to specific items. This helps ensure that you will do the commission in a timely manner, and that it will look good. I also do this to keep commissions as similar to art I would do for myself personally. This allows me to have a closer connection with my commission art. Ever notice how some artists' personal art is much better than their commission art? This is what I do to try to bridge that gap for myself.
2. Use Trello or whatever else to keep track of your commission info - it's easy to get confused or lose info when you are offering on more than one website. Keep your list centralized with all the orders from different sites.
3. Set your prices accordingly - They can't be so high that no one is interested, but they do not need to be so low that you sell slots so quickly that you need to close before getting overwhelmed. Often times, when you post a completed commission, you receive a new order, which keeps a steady flow, and you're working for the max profit for your time spent. Price will differ per artist depending on demand for their art. It can also differ depending on the supply of the art, how much is available to buy.
4. Take payment up front - Some artists accept partial payment; I require full, but I also don't do large pieces. Obviously this just helps guarantee that you won't waste your time on working on something for someone that doesn't end up paying you when it's done. It also makes it a real agreement, and should influence you to begin and complete the work. There are some upsides to taking payment after, however. Firstly, if you don't finish the commission, you don't have to refund anyone. Also, if you take payment after, it gives the commissioner a chance to tip exra if they really liked the work and feel it was worth more than your list price.
5. Don't spend commission money until the commission is completed - Spending money that you haven't earned yet can easily turn into a large pit that you can't seem to get out of. It turns into a downward spiral where you open more commissions to get more money, then owe more art and/or money to another group of people.
6. Don't overload yourself with owed work - Only have as many commissions waiting in your queue as you are able to refund if needed. If you have too many in your queue, you are either working too slowly, or your prices are too low. Close and catch up, and/or raise prices.
7. Accept tips - Make it known you accept tips, or send invoices with tips as an option. I personally add more time to the commission when I receive a tip. How much time depends on how large the tip. If you get lots of tips, it's likely a sign your prices are low or your higher quality work is in higher demand than cheaper work.
8. Use a timer - Like many other artists, I use this timer when I work on commissions: neilblr.com/post/58757345346. It is a very simple, yet very good tool because it only counts time when you are active in a program. You identify which program it keeps track of, so it should work with any art software. I don't think it works on Mac, however. Using a timer can help you come up with a general price for your art, but supply and demand is really going to control that. It's also very good for staying consistent and fair as far as how much time is spent on each commission. It can also help you get focused and stop messing around, and you can speed train with it. It can help you stay focused on what's most important in the drawing, and not waste a ton of time nitpicking on things that don't matter much. If you're doing a 1 hr sketch, and time is almost up but you find yourself stuck on details, it can make you let them go and get the rest of the sketch done. If you are pricing by the hour, it will keep you honest as well. For instance, if you are streaming while you are working on a timed commission, you can stop to chat, eat, surf the web, etc. and still know exactly how much time you've done actual work on the piece.
9. Link to your sale journal when you upload commissions - I actually haven't been doing this lately out of laziness, forgetfulness, and also because i'm winding down the commissions I've been open for. But when you are hoping for another order from someone, it makes it easier for prospective commissioners to find your commission info when it's in the description of the commission you just uploaded, that they really like and want to order one for themselves.
10. Don't move accounts - If you've worked hard to gain watchers on your account, don't abandon them and expect to have the same demand for your art. It's simple math, if you had a lot of watchers on your old account, then made a new one and posted commissions, the post would not reach as many people, so you may get discouraged or have to greatly discount your work to generate more interest, and rebuild your watcher base.
This section is intended ONLY for topics which are no longer relevant, but may be needed for future reference.