I'm going to start writing a book about how I would "fix" Fairy Tail. Not really fixing, but more of making it better and strengthening the plot and characters Mashima had going for him. I love and adore the series, but like most it isn't and will never be perfect.
I won't add or take away characters (unless I have a general idea of someone being added to fix something like a plot hole or I add an idea for an arc)
I also will be keeping the feel of Fairy Tail and the theme. It is also important to realize that the anime didn't have what the manga did for some parts. For example, some characters smoking, blood (more so in the beginning), and even Gildarts wasn't mentioned at the start of the anime compared to the manga. There could be many reasons for these things and so I won't criticize anything like that.