Soft curls are the "it" look right now: perfectly pretty, not too innocent and not too sexy, but nonetheless almost too hard to achieve without the help of a skilled stylist. However, with a little work it's not only possible, but not too difficult, either.
If you have stick straight hair, put a mousse into your hair before you begin, especially if you know your hair doesn't curl easily. Pick whichever mousse you like, but one that announces itself as a curling mousse generally does the job best.
Now, you can go two ways with your style. You can opt to blow your hair out straight and then curl (this is the best option if you have curlier hair) or you can curl as you go. To curl as you go, get a round brush, and while you dry your hair, pull the brush in a circular motion to create a curl.
If you have dried your hair straight, brush it out first and then heat up your curling iron. A ceramic curling iron will work best as it will prevent hair from frying, but if you don't have one, be extra sure to use a heat protectant spray, like the Thermal Protector sprays by CHI. After you do this, section your hair off and curl in small sections. For softer curls, use a larger barrel curling iron and hold for less time. Additionally, releasing the curl horizontally helps. Work your way from the bottom back of your hair gradually to the top and front and look at your curls. If they are too tight, simply work them out a bit with your hands.
Alternatively, if you have very straight hair, you can simply sleep in large rollers. Though this may be hard to get used to at first, it's a great way to curl your hair with little to no hassle.