Fine-hair color and aftercare

Choosing a product.I have light-brown, baby-fine hair that's begging to go silver. The silver, it sparkles, will be pretty in 10 or 20 years. But until then, it will look increasingly mousey. I like my natural shine, and natural red & blonde highlights. And fine-haired thing that I am, I could use some body. I choose color over a perm.Is there a product that would make my gray hair look like natural red highlights without turning my blonde highlights orange? Sort of deepen everything a shade. Something gentle but not flatten my hair, my cuticle is tight enough thank you. In the past, henna left my hair flat, and foil highlights left it brassy and brittle.I've notice women who color their hair tend to get that weird dull look. Is that the nature of hair color over time?Maintenance.What kind of shampoo do I use? Shampoo for fine hair or color treated hair. I love my Lanza shampoo for fine hair. But should I want to give it up to keep a color treatment from getting funky? Will I have to use a conditioner, which always flatten my hair? (My untreated hair is in good shape without them.)