For extra straight hair that you are seeing on TV and in magazines, use good conditioner such as Hayashii 911 and then follow up after drying your hair with a spray on Shine product. You'll have to blow dry your hair straight or use a hot comb or flat iron which are available at all beauty supply stores. You can also get it chemically straightened. There are shampoos that give more body - they actually work giving your hair the appearance of more fullness. Adding highlights and coloring your hair will make your hair much easier to work with and give the appearance of more volume, lift, and thickness.
Shorter haircuts tend to work best for thin hair.
Thanks for your question. I think you should look for a hairstyle that matches your features, however, I think there are more things to consider. My first suggestion is that you research in magazines and find a style that matches the type of hair that you have. My most common request is people asking for styles in magazines with hair types that aren't the same as the model or actress. Ask yourself how much time are you willing to spend on your hair each morning.