Like a nice pair of Jeans, whether they wear plaid (on certain girls it looks great on especially with straight hair)
How well fitting the clothing is (not to say to the extent of skinny jeans but just to complement the figure (usually better I find with curly hair)
How the hair is done
although straight hair mayhave many more styles, do not mistake a good haircut that is for curly as being bad. (there wouldbe a link here but I am one xp away from level 4 making linkage not count, sorry)
but most importantly it dependson the attitude you have, confidence is visible and however you hold yourself will show.
Will people ever search questions before asking the same ones over and over? Ugh. Which hairstyle looks better on you depends on how you look, and what you are wearing. So, you will just have to experiment. Try on different clothes, and makeup with straight hair, look at yourself in the mirror, go out, see what reactions/compliments you get from others, then switch to curly, and repeat.