Regional Worship
Worship in Ancient Greece varied greatly by area. Different groups of Theoi were the focus of worship in different areas. What we think of when we think of "the Olympian Gods" now is Athenian. Most of what we know about religious festivals and practices is also Athenian. This is something that is important to keep in mind. Some reconstructionists like to focus on a specific area or time period. You definitely are not required to do so, but it can be fun to research in its own right.