You want people to visit often and get a lot of value from your content; and then opt-in to your mailing list. If your blog is slow and outdated with broken links, you will lose readers, potential customers, and business partners.
To force Safari to open every link in a new tab you need to use an utility you already have installed on your Mac: the Terminal. To open the Terminal open the Finder, navigate to Applications, from there into the folder Utilites.