A good technique is to come in right behind the crest of a wave. Backpaddle if necessary, to let the wave pass by you, then forward paddle furiously to ride right up on the beach, behind the breaking wave. Keep paddling as it recedes and stop the boat from being sucked back out, with paddle or hands, being careful not to let your paddle get run over by the boat. Compensate for any lateral currents that might sweep you sideways. Unfortunately, you can't always tell what will happen until you get there. Keep bracing into the wave as long as it is headed in, but if it starts receding hard, you may need to reverse your center of gravity abruptly, or you could be capsized seaward and "windowshaded" back out (not pleasant!), especially if the beach is steep, rocky and/or the current is strong.Get out fast and grab your boat, taking care not to get between the boat and the beach, before the next wave creams you. Great fun, when it works! Takes some practice, so try it out in fairly tame surf on sandy beaches first. Have a more skilled person mentor you. Better yet, do that and ALSO get professional lessons, like I did.
If you screw up and the wave starts to break on you, lean back if you're moving forward, attempting to stabilize the boat with your paddle. If you're really strong and the wave isn't, you might be able to backpaddle your way out of a wipeout, but don't bet on it. If you're a good surfer, you might just try to ride it in, but I don't recommend that most people in sea kayaks.
Sometimes a wave will break over me and I can still manage to stay upright while doing this. I keep my center of gravity low and use my paddle to help keep stabilized. If you can carve the wave at an angle, your chances may improve. Most sea kayaks are not good for doing this, but smaller boats designed for surf might be.
If your roll and confidence are excellent, consider capsizing, allowing the wave to break over you and rolling upright after it passes, then paddling in. I have sometimes succeeded at this, but it goes against my instincts. Don't do this if the water is very shallow and/or rocky!
Always try to be familiar with your surroundings, conditions and other paddlers/obstructions in your vicinity. Wearing a helmet adds a margin of safety, but don't get reckless just because your wearing it-- it's not bombproof.
If it feels like the boat may "pearl" dive forward, try to twist/turn sideways into a broach, high brace hard into the wave and hang on! How do you know when this might happen? You probably won't, until it happens a few times and you learn the hard way. Do the same thing if the wave turns your boat sideways on its own. I had that happen Saturday and got surfed up onto a rocky jetty and ended six feet up on the rocks, with no injuries. It was too hairy there for me, with my skill level, to even consider the capsize trick, although I know several people who could have pulled it off splendidly.
Sometimes, you can straighten out from a broach position after the wave breaks and its strength is dissipating, if you sweep stroke forward while in the brace position. Don't forget to keep edging your boat or you'll win "the Kelp Award" for sure. I have a collection of them. Depending on how your boat is sitting and how steep the foam is, you might even be able to backstroke and go in straight backwards (helps to have eyes in the back of your head). I have even seen people do a 360 turn in this manner.
At one time, I used my rudder to help land in surf, but now find that I can handle the boat better without it. It's a good idea to pull the rudder up before you hit the sand (prevent damage and enhance maneuverability on the sand), but you'll need a third arm, if you're trying to maneuver simultaneously.
I am only an intermediate kayaker, aspiring to improve more. I have seen really good surfers do much fancier stuff than I'm talking about (Wayne Horodowhich, Steve Brown, the Schlotters and Duane Strosaker are just a few who come to mind).
Even when back paddling and leaning back is not enough to keep from being surfed in, it will move you farther up the face of the wave. Continuing to brake on both sides can often keep you high enough on the wave to avoid a thrashing, even if you can't get off the wave.