I fine low porosity wavy/curly hair. I started the (modified) curly girl method two months ago, however I had already largely ditched sulfates and silicones in shampoo and conditioner, but some of my hair oils and protein packs contained during alcohols or the odd silicone.
I use a clarifying and chelating shampoo every 4 weeks. The rest of the time I either co-wash with a cleansing co-wash (As I Am coconut co-wash is great), co-wash with normal conditioner and occasionally I use a low poo shampoo (noughty's wave hello which smells divine).
I get the best results with a co-wash, the low poo shampoo can tangle my hair. Co-washing allows to me to gently condition the hair closest to my head while cleansing, without weighing it down.
My hair looks and feels so much better now. It's much less frizzy, and I am really enjoying seeing my hair get curlier - when I gently encourage it to dry straighter it's frizzy and tangled and feels dry, when I encourage my curls it feels much less dry to touch and doesn't look as frizzy 
It's a lot of work though - lots of products (cleanser, conditioner, curl activator, mouse and gel), plus taking the time to wet plop, micro plop and dry plop before diffusing. My hair looks and feels so much better though, and I only need to wash it 3 times a week instead of 6 times a week!
It honestly doesn't look or feel greasy. Trust me, DH would tell me if it did!