I'm still learning but vibrator on clit and vaginal penetration/ g-spot stimulation with vibrator or my partners finger because he can read my body and knows when, where, and how to make it happen! I just forget to relax and let go, trying too hard is what holds me back! Practice makes perfect and I love to practice
My late spouse would squirt, but only during anal sex. She had to be on her back with me kneeling with her ankles on my shoulders when I penetrated her. I suspect that for her, my cock was at the perfect angle to stimulate her g-spot... but not too much. In any case it was a thrilling event for both of us when it occurred. My memories of her and I doing that are among my most pleasant ones.
From what I see you're missing an important option- the combo of g spot and clitoral stimulation. I need hard, fast thrusts with a very curved toy to squirt but I also need clitoral stimulation, often less than if I was getting off clitorally alone (which never makes me squirt) but without something on my clot, its not going to happen. My wife can occasionally get off on G spot penetration alone but she says its a lot better if she gets clitoral stimulation too. From what I've read, that's often the case with many women, g spot alone just won't quite too it and it takes a combination. And stimulating multiple parts of the body at once tends to make for a more intense orgasm whether you're squirting or not.