First, catch your wave
In a way, the hardest thing to get the hang of is catching the wave in the first place. This is not easy - you have to spot the right moment and match speeds with the wave, otherwise it'll go straight past you. The scary-skilled experts just sit on their boards and magically end up moving at the right speed when the wave hits. If you're a normal person, don't even go there.
Your first concern is choosing the right moment. You absolutely cannot just wait for the perfect wave, because it will never ever come. Instead, your thought processes should be a constant stream of "maybe maybe no no yes no no yes yes yes maybe yes YES!!!". You should be ready to throw yourself into the wave that comes, not the wave that you wish would come. There's probably a life lesson in there.
As far as catching up with the wave is concerned, don't even try swimming. Just grab your board and jump onto the wave. Anything else takes more skill than you can muster at this point.
Once you've matched speed and location with a wave, your next goal is to stay with it. This is again harder than it sounds, and it's all about your position on the board. Try going too far forward on your board.
Yes, I mean it. Don't worry, I'll wait.
Tried it? OK, so you faceplanted the ocean. This probably hurt. Don't blame me, I only suggested it. What probably happened is that the tip of your board dipped below water level. As the force of the wave came up behind you, the tip acted as a pivot that flipped the entire board over on top of you.
On the other hand, it's possible to go too far back. Go try it.
Tried it? OK, so the wave went right over you, and you barely moved a metre. Boring, huh? The back end of your board cut into the wave, broke the surface tension and allowed it to go both above and below you without even slowing down.
The trick is as follows. When you first launch yourself onto the board, land with your weight slightly back from centre. This will enable you to catch the wave in the first place. Ensure that your hands are gripping the board further up its length. As the wave passes under you, pull yourself up the board. If you time it just right, you will start to slide down the front of the wave, collecting a serious amount of kinetic energy as you go. That's enough to launch you forward.
The final step
So how do you actually get up on the damn thing? Again, not easy. However, one thing that definitely won't work is putting one foot on and then the other. The board will destabilise and you'll splash.
If you've followed my previous instructions, you'll be gripping the board on either side a fair way up its length. To get upright, you basically need to do a squat thrust. Pull both your feet up the board at the same time, get them simultaneously somewhere near the middle of the board, and push up. Trust me, it'll work.
Well, one time in three anyway. Anything more than that, it's up to you. Let me know how it works for you.