Definitely, there is no excuse for plagiarism. But you can visit your favorite blogs from time to time, as well as make a list of your favorite posts. Then you can write about these ideas and present them by giving your unique perspective.Nevertheless, if you decide to copy any content to make a reference or quote, don't forget to indicate the author's name.
You may enter some writing contest or even start your own.Take a time and explore various topics you could write about, make a list of those. Follow the news and participate in writing contests that correspond to your needs.
Book reviews are important for any kind of blog. Write them in such a way so that you could help potential readers in deciding which books are worth reading. If you write book reviews regularly you will become viewed as an expert reviewer, respected, admired, and, sometimes maybe, hated. Definitely, not every book from your review will be discused positively, and it is absolutely fine.
No matter what your niche is, make a top ten (or more points) list of blogs that are somehow related to it. In addition, consider your top ten favorite movies, books, artists, albums, and anything else you can think of. Your list will be more interesting if you provide useful information about each point on the list.
If you don't know who to interview, bloggers that work within your niche or who write about topics closely related to yours would be a good choice. This is a simple thing to do — just invite them. You may also include the questions you are interested in with your initial request.
Make a top list of the quotes you like most. These can be famous, motivational, inspirational, or any other kind of quotes you find appealing.
You are knowledgeable in your field. Write a detailed post and teach others how to do something. Do it for everything you know and your readers will regard you as an expert, and be thankful for your generosity.
A lot of people love to travel and they often research places which they are planning to visit. You may share your experiences in your blog easily. Tell your readers where have you been, why did you go there and what impressed you the most.
Invite guest posters to contribute to your blog. If there is some area within your niche which you don’t know much about, ask them to fill the gap.
When answering a question in comment or via email, and it is relevant to your readers, write a detailed blog post about it.