In order for your blog to look good, you do not need to make sure that everything you post in it will be coordinated with the theme that you use in your blog. You may want to consider a minimal theme in your blog for it to be simple and easy to match with the contents of your other posts. You need to make sure that you will be able to coordinate everything with your minimal theme wordpress. However, it would not be hard for you to do that because minimal themes are not that hard to match with the contents of your blog. Since it has neutral colors and little designs, it will not interfere with your posts. You just need to make sure that you put good quality of the contents of your posts.
The content of your articles should be of good quality. You should not just put things in your articles randomly. You need to carefully think about the things that you will post there. When you want other people to like your blog, the content of your posts should be with the right grammar and it should make sense. Your readers should get something from it.
When you upload a photo, you may want to consider uploading something of high quality. You do not want your photo to look pixelated due to low quality of pictures. The readers would appreciate it if they see your photos in HD especially if it is the highlight of your post.
Videos can be good for your readers to understand better your posts. Many would not want to read too long articles. In order for them to easily get your point, you may want to include videos of it in your post. However, just like the photos, the videos that you will post should have a high quality for your audience to appreciate it.