what is the best way to have a organism with only your finger???
Your clit. Fingering yourself is not going to give you an orgasm (usually). Only 30 percent of women can have an orgasm from penetration alone.
You can try for a G-Spot orgasm that can be done, but takes time and practice to get right. You stick your finger in your vagina, and make a come here motion with your finger, your g-spot is a spongey feeling area about the size of a nickel, you will feel it when making that motion.
One thing about the G-spot that wasn't mentioned is, when you hit a spot that makes you feel like you have to pee, that's your G-spot. Stay on it.
rub your clit?