Hair, sleek straight shiny

So, I need to know how to actually get sleek, shiny, straight hair.

I have naturally extremely fine, straight hair, and it’s on the thinner side. No matter what products I use, or even if I blow-dry it straight, it always turns out puffy and looks rather dry. They also tend to get stringy

I already use conditioner, but any additional moisture seems to weigh my hair down too much.

Do you have any tips?