The short answer is the simplest one: read the seven novels in publication order, starting with Harry Potter and the Philosopher's Stone (published in some regions as Sorcerer's Stone) and finishing with Deathly Hallows. The series was written and designed to be read this way, and many of its emotional payoffs depend on details planted books earlier.
Publication order also matches the characters' ages, so the books quite literally grow up as you read them. The early titles are shorter, brighter and more episodic; the later ones are longer, darker and more demanding. Reading in sequence lets that shift happen gradually, the way the author intended, rather than dropping you into heavier material before the groundwork has been laid.
Reading in order protects the mysteries, too. The series rewards attentive readers by paying off small, easily missed clues much later, and those surprises only work if you meet them in sequence. Jumping ahead trades that careful craftsmanship for spoilers, and once a twist is known it cannot be un-known.
The full sequence, for reference, is: Philosopher's / Sorcerer's Stone; Chamber of Secrets; Prisoner of Azkaban; Goblet of Fire; Order of the Phoenix; Half-Blood Prince; and Deathly Hallows. That is also the order in which the seven ebooks are presented in this campaign, so you can simply move from one part to the next.
If you are pacing a first read, a comfortable approach is one book at a time with a short pause between the longer middle volumes — Goblet of Fire and Order of the Phoenix are a noticeable step up in length and weight. There is no prize for rushing, and the series rewards readers who let each school year settle before starting the next.
A few readers like to revisit the earlier books after finishing the last one. On a second pass, the early titles read differently: lines that seemed like throwaway jokes or background colour reveal themselves as quiet setup. That is the mark of a series built to be read in order — and a good reason to start at the beginning.