I loved this series as a kid. Being an identical twin myself I was excited to read about the Wakefield twins. You could pick up from anywhere in the series and start reading them. It might have been better that way in case you expected continuity.
I started with this book about a local girl they bully because she doesn't fit in. This turned out to be a common plot in SVT and the high school books.
Even as a kid though I'd be disappointed when none of the books ever delivered on the supernatural plot line.
I recall how silly the Unicorn club Jessica was a member of.