I grew up at the beach and so have my kids. What you want is for them to have a healthy respect for the ocean, not fear. Have them watch the waves and feel their strength at the edge of the water before jumping right in.
As a rule, as long as my kids can stand, I feel like they are safe, they cannot go "over their heads". Teach them to jump over waves and to go under waves that seem to big to jump and to always "just stand up" if they get knocked down by a wave. Part of the fun is getting knocked down and pushed around by the sheer force of the water-something to be appreciated and respected. A favorite game is "pebble" when you sit at the edge of the water when smallish waves are breaking right on shore and just let the water push you wherever it wants.
Boogie boards are great and your kids are not too young especially if they are strong swimmers. Nothing is more fun than riding a wave right into shore.
We don't do all the paraphernalia: noodles, life vests, goggles, for us they just get in the way. We swim, lay in the sand (yup-right in the sand-we call it "shake and bake" when you come out of the water and roll in the dry sand and then jump back in the water), nap in the sun, have beach snacks, listen to the water.
Have fun, the beach is the best.