I am fairly new to blender but I keep running into the same problem when using cycles. The noise is unbearable and I can't seem to find the reason. I followed every advice I could find through google and it all seems to make it worse. If you are interested I have a completed render that I tried to create.
If anyone can help me I would be extremely grateful.
UPDATE: I would like to start by saying thank you for the links and the advice. I have been spending my time just messing around with blender settings and got the noise to clear using a combination of denoising and turning off refractive caustics. I'm not sure how the disabling of refractive caustics helped, but oh well. I have been able to drastically improve the quality of the image, but I would say that it still looks poor quality, but I think I'll look for other questions regarding this issue first. Here is what the finished product looks: