Adjusting the Resolution/Scale

I am trying to get a high resolution map for print so I am exporting via PDF. I am having difficulty working with the zoom. the increments by which it moves is to great. I was told to work with the scale feature to better control the zoom; but I apparently am not properly grasping how this is to be done. Thanks.

Maybe you can find some hints at

Also browse the OSM wiki for more information about SVG output etc.