cutting pictures out with photoshop/photostudio, how do you cut an image out so flawless? Options

[DecentGurl]

alright... i dont know how some people can crop out their images so flawless where they can place it on a different background and it looks nice and not all choppy. do you get what i'm saying...*sighs* if only i had an example...but...i can crop out my images but, i always have a hard time trying to crop out the fellas cause their hair is spikey....and it's hard to get every single spike...and then when i paste it to a new background (let's say white) you'll definately notice that the picture was cropped out all crappy and stuff...is there an easier way or a program that i can use to help? if so...can you lemme know please? thank you!