Any floppy ear breed is more prone to ear infections. GSP's don't have the thicker coat problems that other breeds tend to have. If you think your dog's ear canal looks small or big for his/her body then you might really want to watch it (esp if on the small side).
A good diet is important in overall health.
I keep the hair clipped away from the ear canal to prevent a nice hostile environment for yeast and bacteria which cause the bulk of ear problems. I also use an ear cleaner or wash which acts as a drying agent after our dogs go into lakes and ponds (once a week during the busy part of training/hunting/trialing). It really helps keep the infections down. I also clean the canal with a piece of gauze to remove any visible wax (usually brown in dogs).I have been fortunate to have only a couple of ear infections in the past 12 years with our dogs and those were usually when the older dogs came to us...
Just check your dog over once a week and you'll be aware of changes in his/her body. Check feet, teeth/gums, ears, etc and you'll be aware of potential problems sooner. I try to brush my guys out when I do this and trick the old one into a nail trim when she needs it....Our 9 year old female would tell you that daily ear rubs prevent them too