Having the correct render settings is all relative to the artistic look that you are trying to create.  Here is a general render setting that will be useful for the majority of the non-toon renders that you will probably create.  Below is are the settings that I use for draft purposes only.  These settings give me everything that I need such as shadows and raytracing as well as fast quality draft rendering.  The reason I use these settings is because it helps me to correct any lighting problems, shadow problems, or material problems that may exist without me using a great deal of computer resources to render.  This makes my entire work process faster. Click on the image to enlarge.

Setting the slider to Draft will give you faster renders but it will lack the details that you need to see in order to determine if adjustments in lighting or materials need to be made.  You can use this render setting for draft purposes.  The slider should be placed on Final for photo realistic quality renders, Smooth polygon and Depth of field may also need to be selected depending on the type of model you are using.  Placing the slider anywhere between the custom draft setting shown above and the Final setting will allow you to capture different rendering styles.