Time, Time, and More Time
The primary factor you must consider before starting a blog is just how much time you are willing to invest. A blog, especially if you are not very technically savvy, will require a HUGE time investment. There is a lot to learn both in setting up your blog, promoting the content, and posting. Even if you paid someone to set everything up and to do SEO and promotion, and you just posted content, be prepared to post daily, at a minimum 3 times weekly. A new blog will require plenty of quality content to every turn up in the search engines, so plan on dedicating yourself to daily posts to start.