Steps to take:
1) Do not try to turn it on after removing it from the water. Doing so could cause more damage as you close the circuit to sensitive electronic components by pressing the power switch.
2) Do not plug it into a charger or try to sync it with a computer. Doing so could cause more damage as your "tell" new circuits within the phone to power up.
3) Do remove the battery if possible. (if you cannot easily remove the battery (i.e. Samsung Galaxy), don't try unless you know what you're doing.
4) Find a local repair shop experienced in wet electronics restoration. Believe it or not, your wet phone can almost always be restored to 100% provided it landed in fresh water (salt water is highly corrosive and conductive, so restoration success of ocean bound phones is reduced, and depending on what you do with it after it gets wet (see step 1).
Reputable repair shops will have a good ultrasonic cleaner. If you don't know what an ultrasonic cleaner is, images are below, and read on. :)
Ultrasonic cleaning is a MUST for any wet electronics. Ultrasonic cleaners use high-frequency sound waves sent through a medium, in this case - WATER (with a mild cleaning solution). The sound waves create millions of microscopic air bubbles within the cleaner's basin. These bubbles reach areas you couldn't even think of reaching with a brush. Every nook and cranny water can reach (and you can't) will be microscopically "scrubbed" in an ultrasonic cleaner.
Are you a DIYer with a wet phone and you want to try cleaning it yourself? You don't need to spend a lot of money on an ultrasonic cleaner. My first ultrasonic cleaner was the model in the picture to the right from Amazon. It's just large enough for any phone's logic board, and it works. You don't need a big, fancy ultrasonic cleaner to get started and this one is super easy to use.
In addition to phone parts, the small ultrasonic cleaner from Amazon mentioned above does a fine job deep cleaning jewelry, watches, and just about any other item with small holes/parts where dirt collects that can be submersed in water and tolerate mild cleansers.
Don't forget to pick up some ultrasonic cleaning solution, such as this: