Around 2 years ago, I remember reading about this famous non-IAP player that manage to rank up many +eggs (over 2500) over at the
Puzzle & Dragons Forum. His actual post is in Chinese and on another Chinese forum but hitmantb provided some translation over at the above link.
I thought that play-style was efficient but pretty mundane and true enough, his new 2015 post with updated tips were brought up again at the
Puzzle & Dragons Forum and he actually went on to "semi-quit", as
translated by sdtzpjt. You can't really gather much from Google Translate as a lot of the words used were "short-forms" or nicknames given to the cards but
Kyrdrin did a great job translating most of the tips.
Anyway, I went through the Chinese post again and here are some of the additional things I picked up: