First get a couple extra thermometers to put in the incubator to know the actual temp (don’t trust the incubator temp) and adjust the incubator temp accordingly. Also make sure your turner is working properly or you are hand turning at least 3 times daily. Quality and source of your eggs is also important as is how they are treated pre incubation. Shipped eggs can be great or a disaster and there isn’t much you can do about that. Eggs exposed to freezing temps or heat (80 plus) for a couple hours or more are more likely to have issues as are old eggs (10 days or older at start of incubation). Also tracking when your embryos quit, along with hatch rates etc can help you see trends and identify problem areas. Open your dead eggs and see when they died and possibly why, it Will also help you learn and identify problems.