Don't worry about making your checks perfect. As you color and stain the egg the perfections will blend in. Take a wet rag and add a little bit of paint to it and wipe it over the checks. I like to make vertical lines over the white to add whimsy and color.
Get creative with your designs! It's like egg painting for grown ups.
Once the paint is dry, I like to finish them with a glossy poly and let them dry. This gives them a hard protective, protects your paint and makes them shiny.
You will have them for years to come and they really are pretty. Enjoy!