One lesson learned a hard way. Lace is hard. It’s confusing. If you make a mistake, often the only way to figure it out is to rip the entire thing out and start over. But someone on my Ravelry forum mentioned lifelines. I’d never heard of these, so looked them up.
About every 10 rows, you use a tapestry needle to run scrap yarn through the work where the needle is. Make sure you don’t incorporate the scrap yarn into the work, and keep going. If you make a mistake and need to frog (rippit! rippit!), you can rip back to the lifeline, instead of all the way back to the beginning. The shred of sanity I still had has been preserved!