From my experience, buyable skills are generally safer in moderation. I'm talking herb, craft, cook, high alc, fletch, etc. If you start messing with agility or runecraft then those are easy bans. Ultimately, don't bot anything you care about losing.
I've also had good luck playing normally occasionally on my home IP and botting on a VPN. Accounts have gotten caught but my experience has been positive in appealing and quashed as they said it was abnormal activity.