Why doesn't my hair look shiny and luscious whenever I straighten my hair?

I have dry, coarse and curly hair. You can ume that straightening my hair would take HOURS. I would try different methods so it wouldn't be time consuming, but my hair just doesn't cooperate. when i straighten a small portion of my hair, it takes me 3 times to run it through but it doesn't look nice. it doesn't fall lusciously and it gets frizzy whenever i run my hair through with my hand or a comb. My friend as curly hair and it turns out great when she straightens it. it looks healthy, not frizzy, shiny, easy to run through with your hand without getting poofy and luscious. the only thing is that she doesn't have dry, coarse hair but curly. i've tried a lot of products to restore moisture but nothing is happening. can someone please help? you can recommend products or remedies that may help (other than olive oil i heard it fries your hair like eggs).