Start with this article on Key Principles for Supporting Learning. That is my best overview of all the ideas about early learning you will find on this site, and has lots of links to specifics.

Other helpful overview articles are: Play-Based Learning; Balance of Learning Methods; and Child-Directed Play. Plus a collection of Books and Resources

Then I have several articles related to preschool and school: language and literacy;  academics, supporting non-academic skills for school success; choosing the best preschool / school, and prepping for preschool.

I’ve got lots more info to check out: just click on a category name in the sidebar / links at the bottom of the page, or use the search bar.