Lesson No 1: Surfing is primarily a solo activity - you're on your own buddy!
I remember when I first started surfing. At that time I'd already been skateboarding for a few years and it was natural to try and catch a few waves as well. A few of the skateboarders I knew were also good surfers and they let me borrow a board. But that was as far as it went - no advice offered, no coaching tips, no helping hand. I was given an old board and left to get on with it while they paddled out the back. 'Every man for himself' was obviously the surfer's code. I loved it of-course, who wouldn't? It was fun and exhilarating and totally different to anything I'd tried before.
Lesson No 2: The whole surf/skateboard symbiosis is a myth, they're connected in theory only.
I'd always read that surfing was the original source and skateboarding was the dry land equivalent for when the waves were flat. Well I must have been doing it all wrong, because it was certainly nothing like skateboarding, couldn't be more different in fact. The only relevance was that you were either regular or goofy. Aside from that you're operating in two very different worlds.
Lesson No 3: Surfing is a lot harder than it looks.
Skateboarding can be harsh & gnarly, but if you really want to learn it's relatively easy. Buy a board, find a smooth dry surface and away you go - quite literally. Within a few months you'll be okay at skateboarding. If you've got good balance and some natural ability there's no reason why you can't be ripping within a year or two if you've really caught the bug.
Learning to surf is a lot more complicated. For a start you'll inevitably be on the wrong board (it takes years of riding to even begin to understand which board suits you). You'll need the right waves and conditions for learning, but unfortunately waves don't appear on demand - so this will infinitely lengthen the learning curve. The sea is also deceptive, it moves and changes constantly, no two waves are ever the same, and sometimes it'll be scary and you'll be out of your comfort zone. There's a lot going on that you can't see, currents and tides need to be understood. It's exhausting work, you need fitness and stamina just to catch a few waves sometimes, and of-course you'll be competing with others for the same waves too. You'll also have to learn to 'read' the waves, which will take a ton of time and experience. The list goes on and on.. To summarise - it takes a long, long time to learn to surf.