I know that vetex has stopped devolpment of OPGA but, people still need guides and things to help them in the game as it is.
Method #1- Server Searching
This method involves you going to a random server and looking around each island for a devil fruit, like usual
Method #2- Farming Party-
This method involves having a group of 3 people, to wait at each island for a devil fruit spawn. This allows quick devil fruits, but if you dont get the one you want, after the group is done farming you can choose and trade fruits.
Method #3- Rich Kid's Guide
So as you know VIP servers were added back into the game, this means you can be free of rkers and also have a game all to yourself. Once you spawn in there will be a devil fruit on one of the islands. And every fifteen mins you can look for another one. This method can be enhanced by combing it with A party.
I hope you found this useful, if you think there is another method that should be included please comment and i will add it! w