I rarely if ever sign my shit, since I'm a nameless nobody, I don't think people would steal, even if they do, hell if i ever know, do it or don't, of course it's better to do it, but I'm lazy, and I call myself different name every now n then, so it's not really my thing, i guess.
In the above drawings... 1st drawing: Look at the left pumpkin; 2nd: Right wing... See how there is a "skull" (personalised jolly roger)? Well that's ONE way I do it...
Another way is that I hide maybe 15-20 small signatures ALL over my art... You can be sure that I always sign the crotch and inside of the character's eyes. (I have 2 main signatures, I put both in)
Even this one.. I signed it a bunch. My BF printed this out on canvas (about 1.5m tall? ... and one of my signatures happens to fall pretty much at eye level, and NOBODY ever finds it He's had guests/our friends stare at it for 15minutes! trying to find it.
Another thing I do is that I generally will always add 2 conch piercings on the characters left ear (though if it's the right, it's the right..) They're not particularly common piercings, and it's the piercings I have.
I also add a lot of chrome hearts (brand) accessories and chan luu bracelets. I just add small things that honestly no one would think about but is pretty identifiable with me (esp in combination with everything else I add...)
(I believe my signature should be somewhere in the lipstick left on the guy's chest ).
Here, I also wrote my Maa's chinese name one of the cans, me, my friends, family's birthdays, initials, and a bunch of other 'easter eggs' that are again, very specific to me.
This is usually on top of the jolly roger and signatures everywhere... It's pretty fun honestly, since I also don't remember where/what I put in them, so I can have fun trying to find them.
I don't like adding watermarks to my work either, but I still add them, I try to make the colors blend with the watermark so that people can see it but aren't too distracting.
You could add your signature on a creative way, like if theres a book on your drawing or a sign, you put it there or stuff like that.
Or like some artists do, is to either have a symbol that could be recognized as their own or add something that identifies you. For example, people recognize you from a red banana, maybe it's your creation or a character you made, then you add that banana on every single piece you create. People who know you will be able to tell it's your drawing and if it's been posted somewhere else they're more likely to point it out.
I'm pretty sure some artists just like to post things without watermarks porbably like living life with dangers, are really popular, or just don't care.