The best method to get a popular blog is of course to create new interesting content and share your own knowledge. If you maintain several hundreds of niche sites or write several entries each day it will eventually be difficult to create new content.
When you reach this point it’s a good idea to simple rewrite other people’s information into your own language. For an example, if you maintain a niche site about cars from Ferrari you can simple subscribe to blogs about Ferrari in English and then rewrite their information into your own language.
Remember that’s it not about copying other people’s information but to recreate it. You should not try to create a blog with other people’s entries, but it’s a good method to rewrite their information and post it into a small niche site with different language.
How to find good content
You can find great information on blogs, Wikipedia, books, Amazon, magazines, etc. By simple making a search on Google for your niche + blog, you will most certainly find hundreds of blogs with information about your niche.
When you’ve found a good blog, simple subscribe to it with Google Reader and daily get suggestions for great topics to write about.
How to rewrite other people’s content
When you’ve decided for a specific blog entry or articles you need to read the text twice. Write down main points into a piece of paper or notepad. The close the article and try to never look at it again.
Now you have several good main points which you can search more information about or simple try to write a article based solely on them.
You should never try to translate sentence after sentence since this will make your text look weird and “translated”.