Start with simple forms, like an oval or a circle or something. Studying anatomy, or in this case, a hand's anatomy, will really help you. Knowing where and how the muscles and bones work will definitely help you understand how to draw the hand correctly. Have yet to see a tutorial on hands in English that's really helpful. Though I saw two nice ones on pixiv.
Here's my favorite one, and
here's one I don't remembering bookmarking but apparently did. You don't need to know Japanese to somewhat understand the tutorial, just look closely at the pictures.
Also, female and male hands are different as well. Female hands are rounder while the male hands are squarish, and the bones are more prominent. They're also bigger than female hands, and longer.