Cinema 4D Materials
Grab whatever you want to apply the material too. Now click file < new material in the materials tab, (by default in the bottom right), and double click the new material you just made. Do whatever you want with color. I just chose a darker tone for mine.
Now click reflections. Set the settings at anything you like. I usually leave the color at white, and set it at around 80-90%, so as to not overpower the color. Then click the small arrow and scroll down to fresnel.
Put the settings below in:
Now click specular and play with the settings. I used the ones shown below. Typically, i prefer some variation of these.
Now click transparancy. Leave everything at default and put it at a low-end percentage. I chose around 35-40%.
Optional. Applying a texture
The way to apply a texture is to click the small [...] button besides the large blank button. Find the texture you wish to use, and double click it. Thats about it... I never leave the mix strength at full because it'll overpower whatever color you use. Trust me, 50% may seem weak but its not.
Notice how i placed textures on the floor as well. If i added a light source in, you'd notice a large drastic change in how the reflection reacts. Just play around and you can add a shit load of complexity to a render with it.