I always ask a client for a balayage or blonde do they want a toner and most people don't actually know what they are!
I'm going to explain a little.. toners are a semi permanent colour that changes the tone of your lightened hair! Kind of like your silver shampoo but much better!
In some salons they are called glosses because they also give the hair a really shiny gloss like finish and many people think a toner implies the hairdresser has done something wrong..
In truth pre lightened hair has a raw finish, it tarnishes easily with environmental factors,it may have some yellow in it somewhere, you may have old highlights and some lovely new bright ones a toner/gloss will blend these together!
So should you get a toner.... Hell Yes!
I have toners included in most of my colour work because it finishes my colour off lovely so if your hairdresser asks just say yes you won't regret it! I describe it to my clients as a top coat of gel polish you wouldn't leave your nails with no top coat!
Now how do you pick a toner?
A hairdresser might ask you what tone do you like in your hair.. first thing to do is show them a picture of hair you dream of on pinterest. These are great they give your hairdresser a great insight into what you like and you can start from there. They may suggest a colour for you a hint of beige or ash.. if you don't understand what they are even talking about just trust them we do this a lot and we see the tones in the picture you show us!
If you do or don't like warmth or ash say so!
Your own hairdresser will have their own recommendations on the products they use.