1) If your phone is wet, turn it off as quickly as possible if it isn’t already.
2) If you can, remove the battery on your device as soon as possible. This’ll prevent the internal electrics short circuiting.
3) If your phone was already switched off, DO NOT try and turn it back on.
4) Remove any cases, SIM cards, earphones, SD cards and dry it with a towel.
5) Now you need to get any remaining moisture out of the inside, which you can do at home before turning to the pros to sort it out. You can drain the moisture from your phone by burying it in a container filled with cat litter, cous cous, or instant rice. Seal the container and leave the phone for a minimum of 24 hours.
6) Take it out, reinsert the battery if necessary and hope for the best!
A word of warning: never dry the phone with a hair drier or other forms of heating as this can damage it further.