Caring for straight hair and your new straightened hair style can be difficult, but you should never feel discouraged as there are many ways in which you can care for your new hair style. For that very reason, the most important thing straight hair needs is a gentle shampoo. Choose one that's marked for daily or frequent washing as it's likely to be low in detergents and high in moisturizers. At the very least use opaque shampoo - this tends to include more conditioners and so is kinder to the hair.
Using moisturizing shampoo also means you may be able to get away without conditioner; which is the kiss of death to fine, straight hair as it weighs it down further. If you do want to use conditioning products make sure they are light (sprays are better than creams) and that you wash them out well. Never use leave-in or two-in-one products.
If you want to create some bounce and body in your hair; thickening shampoos are your best friends. These normally include an ingredient called panthenol, which penetrates the hair cuticle, making each strand thicken; plus, they 'negatively charge' the hair so the strands are less likely to stick together.
When it comes to drying, your technique depends on the effect you want to create. For sleek looks, dry hair with a dryer with a nozzle. To create volume, use mousse or thickening gel on the roots of your hair and dry against your natural parting for the majority of the session, tipping your head upside down for the last two to three minutes.