Auto Stores/Sections and Bike Accessories are the best
Scooter Bling! I have lights on my wheels that were made for bikes so they flash/light up as you roll. DH did have to rig them a bit to get them on but they are really fun.
I also got a small press light from the auto store that he attached to my basket for night time. It doesn't really work as a headlight so I can see better, but it makes me more visible to others.
You will find tons of stickers that you can attach on, although you don't have much space. I have several different rhinestone stickers on mine and it gets tons of comments! Also look in the sewing and scrapbooking areas for pretty things you can stick on.
I have also used bike handlebar tassels on my basket (with flowers that spin) and had bike horn for times when I really needed to be heard. However my horn was so popular with the waiters on my cruise last year that I presented them with it on our last night. I now have a bike bell (the old fashioned kind) that is waiting for DH to attach it for me.
I also LOVE my stroller cup holder, left over from when my kids were small. It was made to go over the stroller handle, so now it goes on my tiller handle and holds a drink in the cup and has hanging hooks on the back for bags.
I also have a full size PRINCESS license plate that I bought last time at WDW and will have DH attach around the back of my seat when we go again.
Seat covers are really a must if your seat isn't fabric. That vinyl gets very icky on bare legs in the summer heat. I have a friend that is an amazing seamstress and I just took the chair and fabric to her and she was able to make them with velcro so I can remove them to wash. I keep meaning to get some more fabric to get some different (maybe seasonable!) ones. My current ones are made from Grand Floridian decorative Pillows that I got from ebay. I took the pillow covers (it zipped) and she had no problems. Every seat is going to be different so one pattern won't really fit another.
For others that are looking, I love the model that I have but it is a pretty expensive one. I was very lucky to find it for resale for a great price at our local mobility shop. Mine is a Fold and Go by Rascal
http://www.rascalscooters.com/index.cfm/mobility/products.detail/scooter/Fold-and-Go®-370/id/15 I love that it folds up almost flat and can be stored upright so it takes up very little room. On both of our cruises it would have fit inside the closet if we need it to. It is bigger than the one you are looking at, but I am a bigger size girl and needed something a little sturdier. This one also breaks down to manageable pieces, but even with out that I can put it in and take it out of the back of my van while fully assembled. But I don't have any back or upper body strength issues. If I did then I would have to break it down.
Not a great photo but you can see some of the rhinestones that are on mine, the stroller cup holder
Yes, I was drinking and driving!
In this one you can see the tiller with the rhinestones and my basket in the right side: