Hey, guys (POSSIBLE SPOILERS)
this is my first post.
(i have tried this more than once and it seems to keep working so i assume that it should work for the rest of you)
I found something interesting on dead island riptide.
This is an easy solo or co-op boosting trick.
Firstly make your way to Henderson and go looking for the man on a caravan.
After helping this man he will start to sell mods and parts.
(for those who have finished the game should know what I'm talking about)
Save enough money to buy all of the mods in the shop.
(You may have to fast travel somewhere and come back to refresh the store for more mods)
Once done he'll start to sell blades.
Buy as many blades as you can.
Then fast travel to Saint Maria Church.
For those who have finished the game should know where to go when i say go to the broken helicopter
climb over the log and follow the path around.
you should find a lady.
You may need to complete to missions before getting a continuous one
for every blade you give her (depending on your level) she will give you more money then your spending she will also give XP.
continue going back and forth for more money and XP.