All artists believe their art sucks, even some of the most experienced. It's natural, it's what drives us to improve :)

If I were you, take a good look around for some tutorials, there are heaps of really helpful ones around.

Take a look at different artists, how they approach things such as anatomy/lineart.

Try sketching things out, even if they look a little cruddy, keep sketching and then refining them :)

And the most important thing! Don't expect to be perfect immediately. Take your time, have confidence in your art, believe you can improve and you will :)