Ok I deleted the last post because I mistook 2.3 for the latest version of OceanBlock (oops!) when it is 3.0, which is actually the version I've played, so sorry about the mixup anon. I've got better tips for 3.0, haha.
I have not played 4.0, so I have nothing to add about anything new.
Anyway, here are some tips:
It's annoying to not have stone at all, but as long as you focus on growing tons of trees, you will have resources, which is nice. Just continuously grow trees. A lot of trees. All the time. Seriously. Always be growing as many trees as you can. Nothing is more annoying than running out of wood and having to wait forever to get more.
My biggest suggestion is to pen in the villagers as soon as possible, and build them doors/homes so they can breed. They'll be your biggest resource when it comes to tools. There's diamond, iron, and other ores around, so you'll need some things to trade to get the right tools to mine it. Make as many tradeable items as you can and build up a nice stack of emeralds.
Gather as much dirt as you can to get more grass. If you see this post, you can see how you can get animals to spawn for food, which you can also trade to the villagers.
You need to make a diving platform to get down to the dirt. You don't need to make a hollow tube - just build a pillar of wood down and place ladders on it to create air pockets.
Also, try and get to the Nether as soon as you can. It'll really make your time easier.
After that, just basic survival island/skyblock tips. Spread out your grass, build a mob spawner to get mob drops, and don't go anywhere with anything in your inventory you don't need.
