TRSE: How To Draw Tutorials:
Basics of Drawing the Hands

    This is a fist with firmly closed fingers which may be bit complicated to draw, but you still can draw that fist if you know what sort of patterns and lines to look for. I suggest drawing a circle to outline the entire fist (to control the size of a fist) before adding in the boxy patterns. Again, the fingers are to be the last things to be drawn (blue lines). Keep in mind is that this is a fist that is not holding anything. When a hand is handing an object like a glass of water or a sword, the fingers will be shifted to accumulate the object so if you want to draw a hand holding something, find something similar to hold and use as a model.
 
   Here's more complicated pose of a hand that still can be broken into simple patterns. The "V" sign is very common in Animanga which tend to mean "Victory" or "Two". See how the thumb is positioned in respect to the closed fingers which are touching the palm.

    By learning to read and use the patterns in various poses of the hands even those holding something, the hands will be bit easier to drawn, but even so, they take a good deal of practice. No hand is alike and the fingers of some people can take on some positions that your fingers couldn't take. Best example is Spock(Star Trek)'s famous "Live Long and Prosper" hand signal which some people can imitate while others couldn't. I have seen some more examples in the mangas which my own hands couldn't imitate what the manga artists' unique finger positions, but be careful, the artists can make mistakes with their hands. That's why it's better to trust your own hands than the hands drawn in any artworks.
     It's best to keep the drawing of the hands simple and don't worry about every details of the hands, beside, you won't be able to draw such fine details in the drawings except in the close-up cases. After all, drawing fingernails, wrinkles and even dirt beneath the fingernails are optional, and it's up to you to decide how you want to draw the hands, and having a small mirror handy can be a help too. ^_^