I reckon that your planning to use the flash on camera. So much depends on what you're taking low-light pictures of... portraits, landscapes, action, indoors, outdoors, etc. This makes your question difficult for me to answer in regard to settings because it is very situational. If you have some situation more specific in mind, then you may get more helpful responses.
An on-camera flash is a great way to start. But, pointing your flash at your subject most often doesn't yield the best results. It creates a two-dimensional, flat result. In low light indoors, I "bounce" my flash off a (hopefully) nearby wall or ceiling. For flash outdoors, I mostly use it as a fill light. If you're new to flash, I would recommend the old "strobist" forum as a good reference. The settings change so much with the situation and experimentation and experience are key. If you're already an experienced photographer, then I apologize and admit that I know nothing about the R8 settings.