First ,originality is the key. Your personal opinion on what you are writting about matters. Don't write about what you don't understand.even if you have to research about something, its important that you understand it and explain it in your own way.

Putting your mind away from copying others content will help you a lot. Its not bad to get idea from others but understanding what you are finding solution to is what will help you to stay within your world. Just free your mind when writing, express yourself freely and before you know what's happening, you are done. You can write without plagiarizing. Start with something, just write about anything and see how good it is to express yourself without having to copy from others contents.