I have a layered bob. Hair grey and tending towards dry at the sides. I would like to buy straighteners to add lift and straighten the sides. This will be a new departure and I don't know which to choose. There are at least two really expensive ones in the shops and i am willing to save and buy one of them IF they are effective (for a beginner) and cause the least amount of hair damage. Any advice (and tips) will be much appreciated.