What kind of production; size of egg, frequency of laying, laying well into later years, starting to lay early? Not that it matters to my response, just that you need to define exactly what you are looking for. If you don't know what you are looking for you won't know when you find it. To me, this is the most important step.
Some people can tell you what to look for in conformation or other characteristics of the hen to show which ones have the potential to be good layers. They even have special names to define those characteristics, like “tent”. I can’t do that for you. Hopefully someone else that can will see this and help you out there.
I look at what the hen leaves in the nest. That means you can’t decide on a pullet. You need to give her time to mature so she can show you what her eggs will look like when she grows up. You also need to keep records so you can analyze them and see which hens actually meet your requirements. If you are looking at selecting pullets without a laying history, conformation for potential may be your best way forward.
Since roosters don’t lay eggs, they are harder to analyze. Roosters contribute just as many or even more genes for egg laying than hens because of the sex link genes so they are important. For egg laying purposes, the best I can do is hatch eggs from hens that lay the way I want them to and select a rooster from those chicks. If you know the laying history of not only the mother but of both grandmothers you are a step ahead in this process. You can select cockerels this way.
Other than the obvious size and frequency, I will not keep a hen that consistently lays a bad egg. Determining which hen is laying which egg can be a challenge, but if a hen often lays an unacceptable egg she does not get to breed and pass on her genetics. We all have our own criteria, and a hen that rarely lays a bad egg does not necessarily make my reject list. Any of them can have an oops occasionally. It’s consistency I’m looking at. Some things that get my attention are hens that often lay an egg with a blood spot or meat spot, lay soft or thin eggs shells while the other hens are laying good egg shells, laying double yolk eggs or tiny fart eggs, lay eggs that don’t hatch when incubated, or anything else that indicates the hen’s internal egg making factory is not working the way it should. I’m not too worried about what they lay when they first start laying, it’s what they do once they get the kinks out of their internal egg making system that counts for me.