Probably most crochet designers would agree, that writing the pattern is the most tedious part of being a crochet designer. This is how I do it. If I have a plan before I start, I'll make a goals list including the projected size, color ideas, function of the item (if it's going to be a bag, what do I want it to hold?). If I have no plan in mind, then I just design/play with yarn until an idea develops. I take handwritten notes (I put the date on it, don't forget to write what hook of which brand you are using). When I get the stitches down, I'll make a few more swatches in different colors. Sometimes I'll note the colors in my notes. When I have determined that it will turn into a design to market, I give it an invoice/code number and add it to my list of projects. I get the design a file folder, give it a working title. I type my handwritten notes into the computer and print it out. I make a guess who I might try to sell it to first and put it in that buyers format. I make the item from my typed notes, making corrections as I go. I have to be careful to follow the instructions as if I've never seen them before, because by this stage, I'll usually have memorized the process. When I'm done with the project, I go back and check the math line for line. I check the format that I am writing in. Most of the time, I check the format with recent magazines in hand. I'll find something similar to what I'm writing (rows, rounds, motifs) and see how the tech editors handled things and try to make my instructions agree. I look for how items are spaced, capitalized, abbreviated, etc. (All buyers have slightly different formats for how they want things done). I take lots of photos including super close-ups so that I can understand tricky parts a year from now. If there is a particularly difficult area, I'll include process photos in the instructions. I do this sparingly, though, because adding a photo for illustration is no excuse for not explaining the process in words. You can't just put in a photo and say, "I don't know how to describe this" and then leave it blank. I print out a final copy and put it in my file folder (in case the computer crashes, at least I have a hard copy.)
At this point, I'll submit the pattern to a potential buyer. Whenever possible, I hire another person to tech review the pattern by either making a certain number of motifs, working a few rows, making the whole item, it all depends on how repetitive it is. Then I look at the tech editors suggestions and incorporate them. If the item is already sold, I submit the pattern to the buyer. At this point, the buyer's tech editor may e-mail me if she has questions. Or, even better, the buyer might send me a PDF of the pattern in their format how it will appear in the magazine, and offer me a chance to review it again! (This opportunity is rare, but it is very useful and makes us all look better in the long run).
Finally 6-12 months later the item appears somewhere and you can compare your final instructions to how their tech editor finalized it for publications. This is a great opportunity for learning. Did the tech editor change it not at all, a little, or did she re-write the whole thing? Is her way better? Why is it better and what can you do different next time?
I put all the paperwork, copy of the contract and/or invoice in the file folder. Copy of the contract with the tech editor I hired (if I hired one), a spare yarn label if I have one, and all other details in the file folder. The file folder either goes in my "sold" file drawer, or in the "holding" file drawer.