Select the Zoom Tool from the toolbar
Click on the image to zoom in
Hold Alt on Windows or Option on Mac and click to zoom out
Press Ctrl and plus on Windows or Command and plus on Mac
Use the mouse wheel while holding Alt on Windows or Option on Mac
Press Z to activate the Zoom Tool
Drag a selection box with the Zoom Tool to zoom into that area
Use the Navigator panel to adjust zoom level
Choose a zoom percentage from the bottom left of the document window