Thank you all for your replies and advices. At the moment I'm really focusing on two things: the characters's design and the choice of colors. And i haven't yet the skill of Sinkin !!!
I already do some animation tests that do not make it well enough to be posted. I think once I will control the choice of colors for my sprites, I will focus more on the creation of the hud, objects and maps before to work on animations.
And Sinkin, have any tutorial for create a good palette? because the colors you choose are juste awesome!!!
PS: sorry for my english, i try to do my best ^^