To make a blog more interesting, what should I post ?
Celebrity news, sports news, any videos, or anything other than that ?
Can anybody give me hints ?

If it's a personal blog then you can write whatever you like But if the blog is for the benefit of your website then you should choose a niche that is related with your main site.

Btw, pictures and videos along with a blog post is much more appealing than plain text

There is no formula for creating interesting content. Having a unique and interesting perspective on your topic is just as important as the topic itself. This being the case any one of the topics you mentioned can be interesting in the hands of a good writer.

Personally I'm not a fan of the whole "niche" perspective to blogging. You should write about things you find interesting, not what you think other people will be likely to plug into a search engine. I think you will find it is difficult to offer an interesting viewpoint on things you yourself are not interested in. If you arn't interested in your topic then it is likely that you are just spewing information.

To bring my rant to a close, if you are looking for a topic, the most effective one will be the one you are most interested in (in my non-expert opinion).

make your blog differen with other blog. Post article with fresh content will make your blog more interesting

You have to think to earn. So, you must use right keywords in your blogs.

It depends, interesting to whom?

What I find interesting most of the time may be completely different from what you find interesting. If you don't know the audience you are writing for, then write something that you find interesting. That way the quality of the content will probably come out better too.