There are different ways to mark chickens, depending a lot on what information you want. Some people need a lot of information so they use wing bands or special leg bands that can contain a lot of symbols. One method is toe punching, you punch a hole in the webbing between certain toes on a certain leg for a certain bit of information. With some of these you need to catch the chicken for a close examination to retrieve all the info.
Since you are hatching your own, you cannot use the simple method of buying a different color/breed each year. You can tell their age at a glance.
Probably your simplest method is the colored zip ties. I use the 7" and clip the excess length off so they don't have anything long to peck or get hung up. I've never had a problem with them pecking at it or any indication it bothers them. I use the system of a certain color on the left leg for the year they were hatched and usually two colors on the right leg to identify individuals. When they are walking around it is pretty easy to identify those colors. When they are on the nest laying, well it can be challenging.
Their legs will continue to grow even after they are a year old, but not much. Still, you need to occasionally check even then. I wait until the pullet is probably 4 months old before I band them. The only information I want is the year they were hatched and an ability to tell which pullet is laying which egg so i can determine which I might want to keep as a replacement layer. Or which individuals have gone broody, those are generally keepers. Other people may need information from when they were hatched. Develop your system to give you useful information for you.
Don't use clear as one of your colors, you can't always see it. I avoid using yellow on yellow legged chickens and the darker colors may be a challenge on black legged chickens. Try to use contrasting colors. Blue and purple can be hard to tell apart. Yellow and orange aren't too bad but I've had to pay attention with those. They are still some of my go-to colors. Bright red is another of my go-to colors. I've never had a problem with them pecking at a red tie.
The tendency to go broody is an inherited trait. If you rely on broody hens to hatch it can be challenging, but if you can keep replacements from eggs the broody hen lays you can increase the tendency of your hens to go broody. I'm convinced that going broody can be inherited from her sons too. When I kept a replacement rooster that hatched from a hen that often went broody, the number of pullets and hens that went broody skyrocketed.
Good luck. Like everything else you need to stay on top of it, but I find colored zip ties an easy simple system that works for me.
