Okay, so this is how I do it. I start by creating reasonably sized orders. What I consider reasonable will depend on total order value and how much competition there is. Now, if I can go hours, or even days without being undercut, I’ll just update my existing order. But lets say I update that order, and then get undercut again 10 minutes later. Well, now I’m thinking I want to make a new smaller order, and start updating that. And then, depending on how much people continue to undercut me, I might make an even smaller order, and start updating that one instead. And, of course, if it gets filled, I’ll create another one of equal size.
So, you don’t always need a bunch of orders of each item, but you should have some market slots in reserve so that you can start creating additional orders if needed. Anyway, what you want to do is to get your competition to give up. Make them think that they have better things to do with their time and isk than to compete with you.
iirc, prices are limited to 4 sig figs. Which means that price steps will vary depending on the total price of the item. I just use my scroll wheel to limit the possibilities of errors. For example, if I need to make a small adjustment, I’ll just use the scroll wheel. And if I need to make a new order, or a big price adjustment on an existing order, I’ll enter in the price of the current best order, and then scroll my mouse wheel up or down one step, depending on if I’m buying or selling.