Of course this depends on how much of a soaking you gave your phone. Less is clearly better.
The first thing to do is to remove the battery, second thing to do is to dry it out. Tip it which ever way lets the water run out and sit it on a towel till the water stops.
Now some people recommend putting your phone in a closed container that is filled with rice. Cover the phone with the rice. Supposedly the rice will draw the dampness out of the phone in a few days. Some people use those damp rid packs that are enclosed with goods that get shipped to you. Put a bunch of those in a sealed plastic bag with your phone and wait a few days.
If you are lucky all is well and your phone works.
If you were more creative and used soda to baptize your phone or it is still not working you’ll have to try something more serious. Get yourself some rubbing alcohol, qtips, a soft toothbrush and what ever you need to dismantle your phone. It’s already broken, you’ve voided the warranty you’ve nothing to lose at this point.
Using the toothbrush, qtip and alcohol clean everything. Don’t soak it in the alcohol just clean everything, let it dry and put it back together. If nothing shorted while the phone was wet all should be well.
We’ve also used this method to fix laptops that have been soaked.