I'm guessing "tribbing" is short for "tribadism", which I'm pretty sure is ANY kind of humping or rubbing of a vulva on/against another woman. So, not just in a "scissors" position, but pretty much the same kind of friction happening in all kinds of dry humping, too.
Lots of variations & lots of factors in what might make it feel good to somebody and not another, or in one situation and not another.
Definitely how I started out with my friends when I was little. And it definitely worked.
Instead of trying to make it too much like something you've seen in porn, just naturally just your hips out and do some humping, trying to stimulate your clit and labia against someone's body and engage more of your muscles (in your legs, your butt, your abdomen, etc.). My personal tip is to keep your panties on, at least for awhile, so you can grind and rub and slide around getting hung up on each others specifics.