How to do a flawless and natural presentation?
A natural presentation comes from practice, and lots of it. 

From practice comes confidence. Excellent speakers rarely have more than a few words bullet pointed on their slides. This means that the audience's attention is focused on the speaker. The speaker then tells the audience what the speaker wants them to hear, or directs the audience's attention to an image displayed on the screen.

Aside from not splitting the audience's attention between speaker and loads of text on-screen, having few words on your slides means that you are not tempted yourself to read your presentation to the audience. Such recitation is only suitable if you are analysing the text itself closely.

Further to that last point, having only single or few key words on your slides forces you to know your subject and what to say on each point. You don't have the slides to fall back upon, allowing you to lazily read them to your audience. 

Which brings me back to practice. One way of getting familiar with what you want to say on each point is to write down a few detailed notes for yourself. When you practice your talk, you can refer to these detailed notes. Next time through, distil your notes down to only a few key words. Next time through - or when you are confident - your notes should be only the key words on the screen for the audience, and are therefore redundant. No notes, fluent delivery.