My second smart hijab tip is about what has recently become my favourite type of shoe - the wedge. Wedges are great for both short and tall and I think that they instantly smarten and streamline any look.
As a general rule, I wouldn't wear open-toed or strappy wedges to work, it just doesn't look right. Also, make sure that the trousers almost (but don't quite) hit the ground.
Here's an outfit for some inspiration: