I agree with the above recommendations.
First, make sure to render in a sheet layer viewport, so you can control the resolution. If you are already doing this, then the most likely issues are the DPI of the sheet layer being too low. This is edited in Tools > Organization > Sheet Layers, and then increasing the DPI of the sheet you are rendering on.
Second, If you have that at 150 DPI or above and you STILL see a lack of crispness with the viewport fitting a normal page, increase the Anti Aliasing setting in your Renderworks style.