The HSPT uses certain words frequently, so while you cannot guarantee knowing all the words that could be on the test, you an practice words that are used frequently.
Quizlet has a couple of HSPT vocabulary builders. This resource can also be used for spelling (see the "speller" tool in the top toolbar).
If you need a tour of Quizlet,
To go to the first HSPT vocabulary builder, click here.
A second HSPT vocabulary/spelling list can be found here.