Some plotters can plot both PostScript and non PostScript. Print using PostScript whenever possible. Set page orientation manually. If plotter has orientation control on the panel, make sure it is set in accordance with the PPD layout. Read printer manufacturer's spec for what they consider tall and wide.
Printer times out, quits or prints nothing at all.
Remove unnecessary elements. Remove all objects from the pasteboard. Check for object level halftone setting that is too low. Resize in Macromedia Fireworks or Adobe Photoshop before reimporting. Avoid resizing imported images in Freehand.