My friend has a blind Pit Bull. It had trouble at first (she got it when it was a couple years old) but she figured out it was best to keep it confined to certain areas. She put up gates so the dog could only be in the kitchen and den and he has gotten to know that area very well. She also fenced off a large area in the backyard where she lets him run and play safely.
You can always keep treats around for it and always keep bowls of food close by and in all the rooms in your house so it doesnt have to go searching for where the food is. Talk to the dog a lot and show it a lot of love and affection.
I had lab who went blind. To make her comfortable we did not change the furniture around. We kept everything as it was when she could see. Her food dishes also went in the same place all the time. We were careful to not put obstacles in her way- no shoes in the doorway or her favorite walk ways. A lot of people did not recognize that she was blind, she adapted really well pretty much on her own. Our only real concession to her blindness was to not move things around, be careful to put things away so she did not have hazzards. We probably had a worse time with it then she did. We also walked her pretty much the same path. We did teach her step for steps and and curbs, that way she did not trip on steps and curbs. She also learned to kind of lean onto who ever walked her when we were in strange places. It was something that she learned herself. It really did not seem like a major djustment for her, she seemed as happy blind as she did with her sight. She even managed to fetch and play as well as she did before in our yard.
also see Understanding Cataracts in Dogs
also see The 5 Most Common Dog Eye Problems
also see Aging Dogs: Are Tumors a Concern?