How to avoid?

Not 50-50 at all. 90% chance you won't get banned or better. I've traded huge amounts of money right off of my main. Hopping to f2p, and direct trading. I've never had a rwt ban of any kind, or roll back. Its mostly if you're going to sit at lummy north fountain and trade for 10 hours a day that'll get your account banned.

 

You'll be safe, I've bought and sold some bills from my main account and never gotten a ban.