a couple things i have learned:
1. find a few “Categories” that best fit the subject of you blog.
If you use these categories with your posts, generally you will build a higher rating with engines over a shorter time.
2.Have a categories or tags like “life” or “health” are fine. However a million other blogs use these, and its tough for a new blog to compete. So i use categories that are not as universal,also.
3. make sure you fill out the descriptions if your using pictures!
do not underestimate the power of image search engines to bring traffic to your blog.