I would like to make a "Choose Your Own Adventure" type of story but I'm not sure at all how to.

Can people give me a few tips to start with? Also if I put it on Saimin Booru would people still post on it?

Well of course the first thing is to decide on the premise of it, like a regular story you need to have some idea of how it starts and what the general 'plot' will be.

After that you just kind of make it up as you go based on what feels right and what votes win

I'm just starting so idk if I'm the best person to be dishing advice but I'll give it a try.

IMO the biggest difference between a CYOA and a normal story is that the readers have direct input on how the story progresses, and that must be respected. Think about how much influence you want the readers to have; too little and you might as well write a normal story, too much and you may find it spinning out of your control.

Have a strong central premise that can play out many ways that you're okay with.

Don't put something to a poll unless you have a vague idea of what you'll write for every result. Even the options you think nobody will vote for.

In general CYOAs are more accessible to writing 'by the seat of your pants' instead of a more heavily planned style, because every major choice significantly increases the workload of plotting.

As for putting it on SaiminBooru, I'll admit I don't visit there. Maybe consider posting the same story both here and there?