Hairdressers always compliment my hair as it is thick and straight. But it gets greasy quickly and to my mind often looks flat. I can never decide if I should be using a volumising shampoo as I don't have fine hair by any means. It's just below shoulder length, straight and highlighted. I prefer brands that are towards the organic end and don't mind paying a premium. Have had some success with Aveda but would really like to go 48 hours without washing my hair as drying it bores me. I only put conditioner on the ends and don't use much product. What should I try next?