Before reciting the brachah on the tzitzis, one should check to see if they are intact and kosher (5 knots and 8 strings hanging). Nowadays one may rely on the חזקה that they are still kosher since last time they were checked, but from time to time one should check them again.

Before reciting the bracha one should have in mind that Hashem commanded us to wear tzitzis  in order to remember the mitzvos.