you most certainly can do it all at once.Go to a different salon...or better yet,a haircolor specialist. they have new ways of lightening that dont damage it as much. If you are doing it yourself,you will first want to bleach your hair by buying the bleach lightening kits at a BEAUTY SUPPLY STORE. dont freak when it looks orangey,cuz you must then pick an actual haircolor to put on top of this,such as a light ASH blonde color.If your hair has never been colored,then you shouldnt have too much damage.Just use hot oil treatments,and feel free to leave conditioner in your hair for as long as possible.Also,try frizz ease to smooth hair down and add shine.Highlights may be good to gradually lighten your hair,but are not the long term answer and will cost alot money in the long run. Good luck!