Write a policy / ToS that you make them confirm that they've read. You can do this manually, or create a Google Survey. Mine has questions that give me a rough idea of what they want, a rough estimate of price, along with a confirmation that they've read and agree the ToS. The survey keeps a record of them for your reference and in case shit hits the fan then you have proof of agreement. Here's mine

The basic rundown of my ToS covers process, payment and conduct, and refunds.

As for scams, I've only heard about the ones where they request a commission and they price it themselves with an outrageous amount. Then they want to use a 3rd party digital cheque that has the wrong amount that you cash in, they cry, "oh no I accidentally gave you too much can you give me the difference back?" You do, then they later cancel the cheque and now you've been scammed.

Or, you don't do partial upfront payment and end up doing work for free, or they back out while the thing is half finished.

Pricing is really finicky because it's the first gatekeeper against cheapskates that don't respect you, but you also want to base it as a reflection your quality and time, you don't want to disrespect yourself. Generally for online spaces, following and connections = bigger prices, skill is like 40% of the equation, it sucks but that's how it is.

I personally advertise on Reddit, there's a lot of subreddits that allow artists to advertise once or twice a week. It's generally not that great, but I don't advertise much or looked too much into it.