Came across this article from 2012 at Digital Camera World. and i think it's pretty useful not only for newbies but also those who want to keep on learning what they can in photography
99 Common Photography Problems (and how to solve them)/
here's #1 and you can click on the link above to read more
Problem No. 1: I want to invest in a really good DSLR, but I’m torn between the full-frame and APS-C sensor sizes. What are the pros and cons of each?
A full-frame camera uses a sensor that’s the same size as a frame of 35mm film. APS-C cameras have a smaller sensor based on the size of an Advanced Photographic System film frame. Your choice depends on what type of photography you’re into.
At any equivalent or effective focal length, larger sensors will give you a smaller depth of field – the depth of apparent sharpness in a picture. As a result, the full-frame sensor size is ideal for portraiture, where you want to use a wide aperture to blur the background and make main subjects stand out (to learn more, see Full frame DSLR: do you really need one?).
The flip side is that APS-C cameras can be more useful than full-frame models when you want a large depth of field. If you’re shooting landscapes and want to keep the foreground as well as the horizon in focus, for instance, this can be difficult on a full-frame camera unless you use extremely small lens apertures, which can mean slow shutter speeds (click here for more quick, but great, landscape photography tips).
For sports photography, a top-end APS-C camera such as the Canon EOS 7D or Nikon D300s is a better choice, especially if you’re on a budget. This is because the crop factor gives you a longer effective focal length.
For example, a relatively lightweight 70-300mm zoom lens will give an effective maximum telephoto reach of 480mm on a Canon camera body and 450mm on a Nikon, Pentax and Sony.