Look in the mirror at more than one angle.
I can't believe I have to tell people this. It's like, hey, you're a three dimensional being. The parts you can see in the mirror straight on are only part of the whole! Specifically, when you style your hair, you need to look at the back and sides, and um...not use ugly hair accessories.
So many times I see immaculately dressed women, who *almost* look nice and classy, except for that dollar store hot pink hair elastic holding their pony tail on top of their head. If you must use cheap elastics or (shudder) scrunchies for some reason, at least make them the same color as your hair. And unless you want to look like a teenaged wallflower, just say no to these:
That is all. Have a good weekend!