General reading:
* Carefully: "She read the instructions carefully."
* Slowly: "He read the letter slowly."
* Quickly: "She read the book quickly."
* Silently: "The children read silently."
Specific reading styles:
* Aloud: "She read the story aloud."
* Thoroughly: "He read the report thoroughly."
* Critically: "She read the essay critically."
* Actively: "They read actively, taking notes and asking questions."
Other possibilities:
* Easily: "She read the book easily."
* Loudly: "He read the poem loudly."
* Fluently: "She read the passage fluently."
The best adverb depends on the context of your sentence.