I seem to remember someone once saying that authors often try to find a surname that will be shelved at eye-level, as they're more likely to be picked up on a whim. Personally, I find I'm often drawn to books right beside those by my favourite authors. For instance, if i'm looking to see if a new Simon Scarrow book is out, there'll be another one somewhere in the "s" section that grabs my attention. When I'm just borwsing, I still tend to gravitate towards the areas where I know my favourite authors are shelved - the horror section where Kelley Armstrong & Charlaine Harris sits; the crime section next to Stuart McBride; the sci-fi/fantasy shelves next to Terry Pratchett. After that, it's the general fiction shelves around Scarrow & Brookmyre. I also often pick up new authors when their books are displayed on a table especially if the table is themed, such as historical fiction...