“If you find a book that looks interesting but is part of a series, do you always start with the first title?”
Always, without fail. If you miss the first books you’re going to miss a great deal of character development, not to mention back story. There are some authors who make it a little easier to jump in mid series. An author who comes to mind is Charlaine Harris with her Sookie Stackhouse series (which I’ve read all of!). Although it would be best to read the series from the beginning, at the start of the novels she usually manages to recap some of the major plot turns of the previous book, or she mentions how a new character came to be involved with the series. Not only is that helpful for first time readers, but it jogs my memory as it’s usually been a year since I read the last book.