I cross my sevens, slash my zeros, and use a hook on lowercase T to avoid confusion with plus signs. I think I developed the hook-T habit in college math classes.

That's good, because the "O" should never be dotted. You use slash OR dot for zero, unless you vaguely remember them both as useful for disambiguating but forgot that both marks are for zero and vary by typeface. Mostly dotted zero was just during the dot matrix era. I wouldn't mind being shown counter examples.

I cross my sevens!

I'll consider starting to slash my zeros. Seems legit.