There are many things that you can do with thin straight hair (amazing styles and cuts). You can get it cut in the middle between your shoulders and arms and make a more dramatic part by asking for razor cut hair to get a sharp edgy look. You can have straight hair with or without bangs. If you have a very prominent forehead then bangs are a very good option.
The problem with thin hair is there are not many options that are open to you. Cutting your hair short is not a good choice for person with a big forehead. Instead you can get short bangs above your eyebrows and frame your face with layers.
If you have a small forehead then you can try shorter hair. Another option is for you to try to make your hair thicken by using thickening shampoos. A popular one is Fudge Body Builder Shampoo. Then try a parting to the side so that you get yourself a sort of fringe.
For a high forehead you can use bangs or fringes or a side parting. You can have wispy or heavy bangs based on the style you think suits you better. This helps you to draw attention to your forehead so that the side isn't noticeable.
For thin hair, try something choppy and layered. For example you can use a long shag. Make sure that the shortest layers are styled such that they hit the bottom of your ears. When styling it, you must ensure that you use a pair of scissors instead of using a razor so that the ends of your hair remain feathery.