You'll need a fishing rod and reel. Look for a rod that's about as tall as you are and has a push button reel. You can also use a cane pole (no reel) and tie your own line to the end.
Gotta have bait too—earthworms rule for most fish. You can buy them, dig for them, or find them lying around after a rainstorm. A net will help you scoop the fish out of the water once you've brought them in. You'll also want a basic tackle box to hold your stuff.
Make sure someone knows where you are and how long you will be gone. Check out all the signs where you'll be fishing and stick to what they say. Pick the right spot—stay away from tree branches that hang over the water, power lines, or strong currents. Look before you sit, step, or touch—you don't want to get near animals, or slip on wet rocks. Be careful if you're fishing off a dock or pier so you don't fall in. Check the weather report before going fishing and if a storm sneaks up on you, head for home.
Wear a life jacket if you are anywhere near deep water, running water, or on the ice. Wear a hat and sunscreen to shield you from the rays, and make sure you have your shades on to fight the glare off the water.
Fishing hooks are sharp, so be careful not to hook yourself, or someone else! Keep a first aid kit handy in case you get stuck. Carry a whistle to get help if you need it.
If you want to ice fish (fishing through a hole drilled in the ice), wait until the ice is at least 4 inches thick. For fly fishing (special type of fishing in moving water with bait handmade to look like bugs), shuffle into the flowing current sideways. If you're fishing in the waves, shuffle your feet along to scare away fish and other sea creatures.