Two words: Phone condom.
Invest in a waterproof case.
These can get pricey, but it'll be worth it in the long run. Lifeproof, OtterBox, and DryCase are some great options.
Mashable / Via mashable.com
Stock up on plastic baggies.
If you're going to the beach, you should absolutely put your phone in a plastic bag. It will keep it safe from any water or sand on your hands or in your beach bag.
Jordan Gardone / Via explosion.com
Or use a phone condom.
You read right: Now you can pop your phone into its very own condom. Be safe out there, kids.
Firebox / Via firebox.com
If you drown your phone, immediately use a hairdryer on MEDIUM heat.
You've probably heard of the rice trick, but Gazelle tested and compared it to seven other methods, and they recommend shaking, blowing, and/or vacuuming as much water out as you can before relying on drying agents. Rice, kitty litter, and even a sponge can get out the last few drops, but probably won't save a soaked phone on their own.
Crazy Fixes / Via crazyfixes.com