If i buy hair extensions from sally's...?

not the clip-on kind.

but the kind for weaving.

do you take them to a hair stylist and let them put them on for you?

or what? =/

If i buy hair extensions from sally's...?

Get a stylist to do it they can put them in tightly they will last longer.

If i buy hair extensions from sally's...?

You can, or let someone you know who knows what they are doing, do it. I wouldn't recommend doing it your self unless you are amazingly awesome at it.

P.S.: Don't forget the needle and thread, you'll need those!