Manga/anime drawing is one of the more simple forms of art. The art consists mostly of lines with little etching, shading, and highlighting. Unlike portrait sketching, manga style drawing does not follow anatomical proportion rules to the commas and semicolons. The simplicity of the lines and curves of this form of art makes drawing style drawing popular. Learning how to draw manga style is easier and less daunting compared to learning traditional portrait sketching or even more so conventional oil painting. In just a matter of weeks, people who think they can only draw stick figures, can learn to create manga characters. The important point here is to have fun while learning.
When drawing anime/manga characters on your own, sometimes eyes can be the hardest thing to get right. If the eyes are off, the whole character's expression is thrown off. Eyes are called "the window to the soul" because a person's eyes and eye expressions tell us so much about their personality and feelings.
In a digital drawing tutorials, you may be tempted to make a pair of eyes by simply duplicating and reversing the original. I would advise against this since it looks less natural. What you want is an eye that's similar to the first one, but slightly different, because few faces are naturally symmetrical to that degree.
When I first started drawing manga and trying things out with anime and what not, I soon found out that my abilities were not as great as my imagination. In my head, I wanted to drawing anime full scenarios with amazing, futuristic designs, complex characters with great details and just mind blowing things.