Do you have the camera mode on Auto? I find that the Auto mode doesn't always select the best more. Try selecting one of the indoor modes when indoors and vice versa when outdoors and see if that improves the photos.
I don't have a 710 in front right now but it is generally as follows.
The modes are self explanatory. Select the mode that best describes the situation and you are probably on the right track. It is also a good idea to play around with the various modes in different conditions and you sill see the difference. This will help you select the correct mode for future reference.
With ISO, the higher the number the less light the camera is required for the shot. However, the higher the ISO the grainier the photo becomes. So the darker it gets the higher the ISO should be.
There is no Best setting for all situations. You have to use the appropriate setting different conditions. There are settings for night, day etc. The mode name tells you what it is for. You don't have to be a pro to read that. You can leave it is Auto, but if you do, then you are letting the camera choose the mode to use and sometimes it gets it wrong and the photo quality is not as good.