Many people aren't aware how soft your tooth enamel is; brushing too hard with too stiff a brush can wear it down over time. Use soft bristles, light pressure and your teeth will be much happier.

What about "whitening" toothpaste? I would've thought avoiding that abrasive silica additive was the biggest single factor in avoiding enamel wear. (When I shop for toothpaste, almost every type on the shelf has whitening, so you get it by default.)

Yes this is to be avoided. Whitening at all is harmful, and the book I referenced elsewhere recommends using only "Cavity Preventiion" toothpaste where the only active ingredient is flouride. Also like others mentioned, pH is key - neutralizing it before brushing with an alkalizing mouthwash will help protect your enamel.

Yes, it makes no sense to save little money on your toothbrush, something that you (should) use so ofzen, as the slightly more expensive ones are really worth it!