I have really worn down enamel and generally not the best teeth as well. Genetics definitely plays a huge role in it. My dentist advised me to use PRONAMEL toothpaste. I also use ULTRAFLOSS. Flossing all the time is huuuuge. If you've got bad teeth to start with, not flossing will definitely make them go downhill MUCH quicker.
If you've got dry mouth or you're on medication which induces it, you might want to try BIOTENE mouthwash. Fantastic stuff!
Try to use soft toothbrushes---even for non-sensitive teeth, medium bristles can do more harm than good.
No. 1 terrible stuff for teeth is energy drinks. Sugar free or not, they're terrible for your teeth. If you HAVE to drink them, do it through a straw. Just read a study, too, that shows brushing IMMEDIATELY after drinking them is even worse for your teeth. Rinse out really well with water after drinking energy drinks or soda and then wait a bit to brush.
And seriously...wear a mouthguard when you're doing any kind of sport. I've had my tooth chipped skydiving, and I'm really really lucky I've never lost one in any of my cycling accidents or wakeboarding.
Aside from some stains, some crooked, and an overbite, I'm not extremely extremely unhappy with my teeth. I would probably consider braces to straighten out a bit and perhaps some whitening...but it's all ridiculously expensive!!!
