I'm not 100% sure, but some I've heard of are: having sexual relationships unprotected with the intention of getting an STD, skin picking, hair pulling, nail biting, hitting yourself, scratching and self-induced vomiting. I say I'm not entirely sure because actions like skin picking or hair pulling aren't always done to harm oneself, but are provoked in repetition due to a mental disorder. I guess it depends on the intention.
There's also digital self-harm, which is when you seek negative things about yourself or that are triggering via social media, make negative or threats about yourself, and so forth.